;-NRLF 


THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

DAVIS 


• 


University 

Davis.  California 


A  TREATISE    ON    CRANES. 


A    TREATISE 


ON 


CRANES 


DESCRIPTIVE  PARTICULARLY  OF  THOSE  DESIGNED  AND  BUILT  BY 
THE   YALE  &   TOWNE   MANUFACTURING   CO., 

OWNING  AND   OPERATING 

THE   WESTON   CRANE   CO. 

INCLUDING  ALSO  A  DESCRIPTION  OF  LIGHT  HOISTING  MACHINERY 
AS  BUILT  BY  THE  SAME  MAKERS. 


BY      - 

HENRY    R.    TOWNE, 

MECHANICAL    ENGINEER. 


STAMFORD,  CONN., 

1883. 


UNIVERSITY  OF  CALIFORNIA 

^OT?\TTA  i  it  ix-  A  - 


Entered  according  to  Act  of  Congress,  in  the  year  1883,  by 

HENRY  R.  TOWNE, 
In  the  office  of  the  Librarian  of  Congress,  at  Washington. 


PRINTED   BY 

E.  8.   DODGE,  STEAM  PRINTING  HOUSE, 
95  CHAMBERS  ST.,  N.  Y. 


PREFACE. 


The  subject  of  Cranes  has  had  but  little  consideration  from 
technical  writers,  and  has  never  yet  received  from  them  the 
attention  which  its  importance  in  the  mechanic  arts  will  justify. 
It  is  perhaps  partly  due  to  this  cause  that  the  value  and  economy 
of  Cranes,  as  labor-saving  machines,  is  as  yet  so  little  appreciated 
in  this  country. 

The  only  English  books  descriptive  of  Cranes  are  that  of 
Glynn,  written  more  than  thirty  years  ago,  and  the  catalogues 
published  by  various  English  firms  to  advertise  their  products, 
none  of  which  fully  represent  what  is  best  in  English  practice, 
or  affords  any  information  as  to  the  important  details  of  con- 
struction embodied  in  the  machines  they  illustrate. 

The  present  treatise,  although  intended  primarily  to  place 
before  users  of  Cranes  a  description  of  those  built  by  THE  YALE 
&  TOWNE  MANUFACTURING  COMPANY,  includes  a  careful  study 
of  the  subject  from  an  independent  point  of  view,  and  will,  it  is 
believed,  be  found  of  interest  to  engineers  generally  by  reason 
of  its  comprehensiveness,  both  as  relates  to  the  various  types  of 
Cranes  and  to  the  details  of  their  construction,  and  because  it 
carries  the  art  it  describes  down  to  a  more  recent  date  than 


VI 

any  previous  publication.  In  its  description  of  details  and  of 
actual  construction,  it  embodies  the  results  of  the  combined  work 
of  several  skilled  inventors  and  mechanical  engineers,  continued 
uninterruptedly,  under  the  author's  direction,  during  a  number 
of  years  and  applied,  together  with  the  resources  of  a  large 
establishment,  to  the  study  and  development  of  the  art  of  Crane 
building  as  a  distinct  specialty. 

It  is  the  first  publication  descriptive  of  American,  as  distinct 
from  European  practice,  in  the  specialty  of  which  it  treats. 
The  class  of  machines  which  it  describes  has  long  been  recog- 
nized in  Europe  as  one  of  wide  importance  and  interest.  It  is 
the  purpose  of  this  treatise  to  indicate  to  American  readers  the 
great  variety  of  uses  to  which  Cranes  can  be  applied  with 
economy  and  convenience,  and  to  describe  the  latest  and  best 
results  of  American  practice  in  this  field  of  engineering  work. 

H    R    T 
September,  1883. 


Vll 


CONTENTS. 


PART  I. 

PAGE. 

Introduction I 

Types  of  Cranes 3 

Details  of  Cranes : 

Hoisting  Gear 6 

Traverse  Gear 9 

Chains  versus  Ropes,  and  Chain  Wheels  versus  Drums n 

Trolleys  and  Trucks 15 

Frames  and  Girders 16 


PART  II. 

Introduction 21 

Crane  Details 22 

Chains 23 

Chain  Wheels 25 

Spur  Gearing 28 

Worm  Gearing 30 

Frictional  Safety  Ratchet 33 

Clutches 41 

Weston-Capen  Clutch 47 

Squaring  Device  for  Movable  Crane  Bridges 54 

Bridge  Moving  Device  for  Traveling  Cranes 58 

Squaring  and  Bridge  and  Trolley  Moving  Device  for  Traveling  Cranes. ...  61 

Trolley  Traveling  Mechanism 65 

Gearing  of  Jib  Cranes  for  operation  by  Hand 69 

Gearing  and  Clutches  of  Power  Traveling  Cranes 73 

Bridge  Trucks 78 

Frames  and  Girders 8 1 

Bridges  and  Trestles  of  Traveling  Cranes. 85 

Power  Transmission 88 

Take-ups 90 

Hooks 91 

Blocks  and  Bushings 94 

Pillar  Crane  Foundations 97 

Notice  as  to  Rights  Secured  by  Patent 99 

List  of  Patents 103 


viii  Contents. 

PART  III. 

PAGE. 

Introduction 107 

Swing  Crane,  with  Winch,  without  Trolley 108 

Light  Jib  Crane,  with  Differential  Pulley  Block  and  Trolley no 

Light  Jib  Crane,  with  Winch,  Trolley,  and  Traverse  Gear 112 

Jib  Crane,  Independent  Trolley  Travel 115 

Jib  Crane,  Combined  Hoist  and  Trolley  Travel 118 

Column  Crane 122 

Walking  Crane 124 

Rotary  Bridge  Crane 127 

Derrick  Crane. ...    130 

Pillar  Crane 132 

Locomotive  Crane 135 

Bridge  Crane 136 

Hand  Traveling  Crane,  for   Differential  Pulley  Block,    Longitudinal  Tra- 
verse Gear  only 140 

Hand  Traveling  Crane,  for  Differential  Pulley  Block,  with  Transverse  and 

Longitudinal  Traverse  Gear 143 

Hand  Traveling  Crane  (High  Pattern),  with  complete  Hoisting  and  Travel- 
ing Gear 146 

Hand  Traveling  Crane  (Low  Pattern),  with  complete  Hoisting  and  Travel- 
ing Gear 149 

Hand  Traveling   Crane  (Foundry   Pattern),  with  complete  Hoisting   and 

Traveling  Gear 152 

Power  Traveling  Crane 155 

Power  Traveling  Crane,  Double  Trolleys 160 


PART  IV. 

Introduction 165 

Relation  of  Power  to  Speed 167 

Principle  of  the  Weston  Differential  Pulley  Block 168 

Differential  Pulley  Block,   "Direct " 176 

"Geared" 177 

Safety  "  Double  Lift "  Hoist 178 

"  Safety  "  Hoist 180 

"     with  "Governor"  Action 181 

Hoisting  Crab 183 

Derrick  Winch ,  ...  184 

Dredging  Winch 185 

Light  Swing  Crane,  with  "  Double  Lift "  Hoisting  Gear 186 

Overhead  Tramrails,  Single  Rail 187 

"  "         Compound  Rails 190 


Contents. 


INDEX  TO  ILLUSTRATIONS. 


PAGE. 

Fig.    I.     Chain  Wheel,  Guide  and  Stripper 26 

V     2.     Teeth  of  Spur  Wheels , 28 

"     3.     Worm  Wheel  and  Worm 32 

"     4.      "  Double  Lift  "  Safety  Ratchet 34 

"      5.     Spur  Pinion  with  Safety  Ratchet 36 

"      6.     Safety  Spur  Pinion 3§ 

"     7.     Safety  Worm  Pinion 40 

"     8.     Model  of  Alternate  Friction  Plates 4* 

' ''     9.     Experimental  Friction  Brake 43 

11    10.     Frictional  Shaft  Coupling,  longitudinal  section 44 

"    ii  &  12.      "           "             "        transverse  section 45 

"    13.     Friction  Pullies  with  Capen  Toggles 47 

' '    14.     Simple  Form  of  Weston  Clutch 49 

"    15.     Weston  Clutch  with  Capen  Toggles 5° 

"    16  &  17.     Capen  Toggles 51 

';   18,  IQ&20.     "         <• 52 

"   21.     Device  for  Squaring  Movable  Bridges 54 

"   22.     Device  for  Squaring  and  Propelling  Bridges 5^ 

"   23.  Device  for  Squaring  and  for  Propelling  Bridges  and  Trolleys. ...  62 

' '   24.     Mechanism  for  Moving  Trolleys 66 

"  25.     Gearing  of  Jib  Cranes 69 

' '   26.     Detail  View  of  Chain  Wheel  in  Jib  Cranes 70 

"   27.     Gearing  of  Jib  Crane 71 

"   28.     Top  View  of  Reversing  Mechanism 74 

"   29.     Side  Elevation  of  Reversing  Mechanism 74 

"   30.  End  View  of  the  Three  Shafts  of  the  Reversing  Mechanism  and 

their  Connecting  Gears 75 

"   31.     Truck  for  I-Beam  Bridge 78 

"    32.     Truck  for  Plate  Girder  Bridge 79 

"   33-     Jib  Crane  Frame 82 

"   34.     Transverse  Section  of  I-Beam  Bridge 83 

"35-              "                "        "  Plate  Girder  Bridge 83 

"    30.     Bridge  of  Hand  Traveling  Crane 85 

"37.          "       "Power         "             "     86 

•'   38.     Rim  of  Wheel  for  Wire  Rope 88 

"39-       "     "       "        "  Cotton  Rope 88 

"  40.     Transmission  of  Power 89 

"   41.     Take-ups 90 


x  Contents. 

PAGE. 

Fig.  42.     Standard  Hook 92 

"  43.     Crane  Block  and   Hook 94 

l<  44.     Anti-Friction   Bushing 95 

"  45.     Pillar  Crane,  and  Foundation 97 

"  46.     Swing  Crane,  without  Trolley 108 

''  47.     Light  Jib  Crane,  with  Trolley  and  Pulley  Block no 

"  48.          "       "       "           "         "           "    Winch 112 

"  49.     Jib  Crane,  with  Separate  Trolley  Gear 116 

"  50.      Heavy  Jib  Crane,  with  Combined  Gear 118 

"  51.  Column  Crane,  or  Jib  Crane  swinging  around  a  Fixed  Column. .    122 

<4  52.     Walking  Crane,  as  arranged  for  operation  by  Power 124 

"  53.     Rotary  Bridge  Crane 128 

"  54.     Derrick  Crane,  for  Outdoor  Use 130 

"  55.     Pillar  Crane,  for  operation  by  Hand 132 

"  56.     Bridge  Crane,  operated  by  Hand 136 

"  57.          "           "           "           "Power 138 

58.  Light  Hand  Traveling  Crane,  Longitudinal  Traverse  Gear  only. .    140 
"59.  "       "  "             "        Transverse  and   Longitudinal  Tra- 
verse  Gear 144 

"  60.     Hand  Traveling  Crane,  with  Overhead  Trolley 146 

"  61.          "             "             "         "      Underhung  Trolley 150 

"  62.          "             "             "         "      Fixed  Crab 152 

"  63.     Power  Traveling  Crane,  with  Single  Trolley 156 

"  64.  "             "                                                "       as  applied  to  Foundry 

Use 159 

65.     Power  Traveling  Crane,  with  Two  Trolleys 160 

"  66.     Principle  of  the  Weston  Differential  Pulley  Block 169 

"  67.            "          "     "         "                "                  "          "      170 

"  68.     "Direct"  Differential  Pulley  Block 176 

"  69.     "Geared"                           "         "      177 

"  70.     Direct  "  Double   Lift"  Hoist 178 

"  71.     Geared         "           "          "     179 

"  72.     "Double  Lift,"  as  Used  for  Hatchway 179 

"  73.     "Safety  Hoist" 180 

"  74.             "         "        with  "Governor" 181 

"  75.     Safety  Crab 183 

"  76.     Safety  Winch 184 

"  77.     Safety  (Slip)  Winch 185 

"  78.     Light  Swing  Crane,  with  "  Double  Lift  "  Hoisting  Gear 186 

"  79.     Single  Tram  rail 187 

"  80.     Patent  Trolley,  Side  elevation 188 

"  81.          "             **       End  View 188 

"  82.     Single  Tramrail,  with  Switch 189 

"  83.     Compound  Tramrail 190 


PART   I. 


PART    I. 


INTRODUCTION 


The  contents  of  this  Part  consist  of  a  general  survey  of  the 
subject  of  Cranes,  including  an  enumeration  of  the  principal 
forms  in  which  they  are  used,  a  definite  system  of  nomenclature 
applied  to  the  various  forms,  and  finally  a  study  of  the  most 
important  elements  of  mechanism  employed  in  Crane  construction. 

The  latter  portion  is  in  some  measure  a  record  of  the 
processes  of  reasoning  and  selection  which  resulted  in  the 
adoption  of  the  forms  of  details  employed  in  the  Weston  Cranes. 
In  undertaking  this  new  field  of  work  the  builders  of  these 
Cranes  were  untrammeled  by  any  previous  position  or  bias  as  to 
the  details  of  the  work,  and  many  months  of  careful  study  were 
given  to  the  consideration  of  the  best  forms  to  be  adopted.  The 
process  usually  resorted  to  in  this  effort  was  to  give  equal 
consideration  to  all  possible  plans  and  to  select  therefrom  the 
one  which  gave  the  best  promise  of  satisfactory  results.  The 
decisions  thus  reached  were  then  subjected  to  the  test  of  practice, 
and  further  modifications  and  improvements  were  introduced 
as  experience  was  gained.  The  effort  throughout  was  to  reach 
the  best  practicable  result,  and  to  determine  finally  and 
reliably  the  best  form  or  method  of  construction  for  each  of 
the  important  details  of  Cranes. 

The  following  pages,  therefore,  are  not  immediately  descrip- 
tive of  the  Weston  Cranes,  but  comprise  a  preliminary  review  of 
the  whole  subject  which  will  enable  the  reader  to  understand 
the  reasons  upon  which  the  selection  of  the  chief  elements  in 
the  Weston  Cranes  are  based,  and  will  assist  him  in  judging  for 
himself  as  to  the  soundness  of  the  conclusions  reached  in  the 
succeeding  parts  of  this  book. 


A    Treatise  on  Cranes. 


CRANES; 


A   STUDY  OF   TYPES   AND   DETAILS, 

BY 

HENRY   R.  TOWNE. 


A  paper  read  before  the  American  Society  of  Mechanical  Engineers, 
at  the  Cleveland  meeting,  June,  1888. 


In  the  study  of  any  special  class  of  machines  it  is  often 
conducive  to  a  better  understanding  of  the  subject  clearly  to 
enumerate  the  several  types  or  forms  in  which  the  machine  is 
used,  and  also  to  consider  each  of  its  more  important  details 
separately,  rather  than  in  their  combination  with  other  elements 
of  the  mechanism.  It  is  proposed  in  the  following  pages  thus  to 
treat  the  subject  of  Cranes. 

The  only  English  text-books  descriptive  of  cranes  are 
Glynn's,  which  treats  of  English  practice  in  crane  building  as  it 
existed  more  than  thirty  years  ago,  and  sundry  catalogues 
published  by  English  dealers  in  machinery  as  a  means  of  adver- 
tising the  products  of  the  various  builders  of  cranes  for  whom 
they  act  as  selling  agents.  The  practice  represented  in  the 
former  is  now  almost  obsolete,  by  reason  of  the  improvements 
which  have  been  effected,  and  the  latter  consist  of  little  but  a 
series  of  pictures  of  various  cranes,  without  descriptive  text,  and 
with  no  information  as  to  the  details  of  their  construction. 

The  building  of  cranes  has  long  been  recognized  in  Europe 
as  one  of  the  most  important  subjects  in  the  field  of  mechanical 
engineering,  and  cranes  of  many  forms  are  there  seen  applied  to 
an  almost  infinite  variety  of  uses.  In  America,  on  the  contrary, 
cranes  are  but  little  used  or  appreciated,  in  comparison,  at  least, 
with  the  extent  of  their  application  in  European  countries.  It  is 


Types  of  Cranes. 

the  purpose  of  this  paper  to  present  to  American  readers  a  brief 
classification  and  description  of  the  most  important  types  of 
cranes,  and  a  similarly  brief  study  of  the  more  important  elements 
entering  into  their  construction,  the  object  of  the  latter  inquiry 
being  to  determine,  if  possible,  the  best  forms  of  elements  to  be 
adopted. 

With  a  better  knowledge  of  crane  construction  will  surely 
come  a  better  appreciation  of  their  economy  and  value  as  labor- 
saving  machines.  In  hundreds  of  mills  and  workshops  heavy 
material  is  now  being  moved  and  handled  by  manual  labor  at  an 
expense  so  much  in  excess  of  the  cost  of  doing  the  same  work 
far  more  rapidly  and  conveniently  by  cranes,  that  the  saving 
effected  by  the  latter  would  yield  an  annual  profit  of  from  twenty 
to  fifty  per  cent,  upon  their  first  cost,  while  in  many  cases  this 
outlay  would  be  entirely  repaid  by  the  economy  of  one  year's  use. 

CLASSIFICATION    OF    CRANES. 

A  hoist  is  a  machine  for  raising  and  lowering  weights.  A 
crane  is  a  hoist  with  the  added  capacity  of  moving  the  load  in  a 
lateral  or  horizontal  direction. 

All  cranes,  therefore,  are  provided  with  hoisting  mechanism, 
and,  in  addition,  must  be  capable  of  moving  the  load  in  one  or 
more  horizontal  directions.  This  second  function  is  effected  in 
some  types  of  cranes  by  simply  pushing  the  suspended  load,  in 
others  by  the  operation  of  a  distinct  mechanism. 

Cranes  are  most  clearly  classified  by  reference  to  their  modes 
of  transferring  their  loads  horizontally  ;  and,  thus  considered,  are 
found  to  divide  themselves  into  the  following  groups,  viz. : 

1.  Rotary — In  which   the  load   is  revolved   around  a  fixed 
center,  such  as  a  mast  or  column. 

2.  Rectilinear — In  which  the  load  is  moved  in  straight  lines, 
in  one  or  more  directions. 

Both  types  of  cranes  are  subdivided  into  two  general  classes 
as  to  their  movements,  viz.: 

(A.)  Fixed — When  their  supporting  members  are  fixed  in 
some  permanent  location. 


4  A    Treatise  on  Cranes. 

(£.)  Movable — When  the  crane  as  a  whole  can  be  moved 
about. 

And  into  four  other  general  classes  as  to  their  source  of 
motive  power,  viz.: 

(a.)  Hand — When  the  motions,  either  vertical  or  horizontal, 
are  effected  by  manual  power. 

(b.)  Power — When  the  motions  are  effected  by  power  derived 
from  line  shafting  driven  by  a  stationary  engine  or  other  fixed 
motor. 

(<;.)  Steam — When  the  motive  power  is  derived  from  a  steam 
engine  attached  directly  to  the  crane  itself  and  moving  with  it. 

(d.)  Hydraulic — When  the  motive  power  consists  of  hydraulic 
pressure  obtained  from  a  pump  or  accumulator,  and  carried  to 
the  crane  by  pipes. 

A  further  distinction  is  covered  by  the  term  locomotive, 
which  is  applied  to  cranes  (usually  of  the  rotary  type)  which  are 
capable  of  propelling  themselves  upon  a  roadway  or  track. 

Rotary  cranes  comprise  the  following  principal  types,  viz. : 

1.  Swing  Cranes — In  which  the  central  mast  is  pivoted  to  the 
floor  and  roof  of  the  building,  and  the  load  is  suspended  from  a 
block  fixed  at  the  outer  end  of  an  arm  projecting  horizontally 
from  the  mast,  the  only  horizontal  motion  being  one  of  rotation. 

2.  Jib  Cranes — In  which  the  central  mast  is  pivoted  to  the 
floor  and  roof  of  the  building,  and  the  load  is  suspended  from  a 
trolley  traveling  in  and  out  upon  an  arm  or  jib  projecting  laterally 
from  the  mast. 

3.  Column   Cranes — Which  consist  of  a  jib  crane  constructed 
to  revolve  around  or  upon  a  fixed  column  forming  the  support  of 
a  building  or  floor. 

4.  Pillar  Cranes — In  which  the  central  column  or  pillar  is 
entirely  supported  by  a  heavy  foundation  built  at  its  base,  and  the 
load  is  suspended  from  a  boom  projecting  from  the  pillar  and 
revolving  with  it  or  around  it. 

5.  Derrick  Cranes — Which   consist  of  a  jib   crane   for  yard 
use,  the  upper  end  or  pivot  of  the  mast  being  held  in  position  by 
guy-rods  or  stays,  instead  of  by  attachment  to  a  roof  or  ceiling. 

6.  Walking  Cranes — Which   consist  of  a  pillar  or  jib  crane 


Types  of  Cranes.  5 

mounted  on  wheels,  and  arranged  to  travel  by  power  or  by  hand 
upon  one  or  more  rails. 

7.  Locomotive  Cranes — Which  consist  of  a  pillar  crane 
mounted  on  wheels,  and  provided  with  a  steam  engine  and 
boiler,  the  power  of  which  is  available  for  operating  the  crane 
and  for  propelling  it  upon  its  tracks. 

Rectilinear  Cranes  comprise  the  following  principal  types: — 

1.  Bridge  Cranes — In  which  a  fixed  bridge  spans  an  open- 
ing, and  the  load  is  suspended  from  a  truck  or  trolley  capable  of 
moving  across  the  bridge. 

2.  Tram  Cranes — In  which  a   truck  or  short  bridge,    from 
which  the  load  is  suspended,  is  arranged  to  travel  longitudinally 
upon  a  pair  of  overhead  rails,  but  is  without  capacity  for  trans- 
verse motion. 

3.  Traveling  Cranes — In  which  a  rectangular  space  is  pro- 
vided with  overhead  tracks  upon  two  of  its  opposite  sides,  and  is 
spanned  by  a  bridge  arranged  to  travel  longitudinally  upon  these 
tracks,  the  load  being  suspended  from  a  truck  or  trolley  capable 
of  moving  transversely  across  the  bridge,  so  that  the  load  may 
be  moved  to  or  from  any  point  within  the  entire  rectangle. 

4.  Gantries — In  which  an  overhead  bridge  is  supported  at 
each  end  by  a  frame,  or  trestle,  extending  downwards,  and  having 
wheels  in  its  base  to  permit  of  travel  upon  two  longitudinal  tracks 
laid  upon  the  ground,  so   that   the   entire  structure  can  move 
endwise  upon  the  latter,  and  the  load,  which  is  suspended  from  a 
truck  or  trolley  on  the  bridge,  can  be  moved  transversely  across 
the  bridge. 

5.  Rotary  Bridge  Cranes — Which  combine  a  rotary  with  a 
rectilinear  movement,  and  consist  of  a  bridge  having  one  end 
pivoted  to  a  central  pier  or  post,  while  the  other  or  outer  end 
travels  on  a  circular  overhead  track,  or  is  supported  by  a  gantry 
frame  traveling  upon  a  circular  track  upon  the  ground,  the  load 
being  suspended  from  a  truck  or  trolley  traveling  transversely 
across  the  bridge. 

The  above  nomenclature  will  be  adhered  to  in  the  following 
descriptions  of  crane  construction. 


6  A    Treatise  on  Cranes. 

CRANE    DETAILS. 

HOISTING    GEAR. 

The  most  important  factor  in  the  economy  and  convenience 
of  a  crane  is  the  mechanism  by  which  the  load  is  lifted  and 
lowered,  as  it  must  necessarily  come  into  action  every  time  the 
crane  is  used. 

In  all  applications  of  power,  from  whatever  source  derived, 
it  must  be  remembered  that  the  gearing  of  a  machine  can  only 
modify  the  power  applied  in  one  of  two  ways,  viz. : 

(i).  By  reducing  its  velocity,  and  proportionately  increasing 
its  force  or  "pull." 

(2).  By  increasing  the  velocity,  and  proportionately  decreas- 
ing the  intensity  of  the  power  transmitted. 

Under  no  circumstances,  unless  the  motive  force  is  increased, 
can  power  be  gained  except  by  a  sacrifice  in  speed,  or  can  speed 
be  increased,  except  by  a  sacrifice  in  power.  If  either  or  both 
must  be  increased  without  diminishing  the  other,  it  can  only  be 
accomplished  by  supplying  more  motive  power. 

The  function  of  gearing,  then,  is  to  change  the  force  or 
direction  of  the  power  applied.  If  it  is  well  designed  and  con- 
structed, this  may  be  done  with  only  a  small  loss  from  friction; 
while,  if  badly  made,  the  gearing  may  absorb  much  power  in 
wasteful  friction  of  its  moving  parts. 

In  machinery  for  hoisting,  the  "  purchase  "  or  conversion  of 
velocity  into  lifting  power,  is  usually  effected  partly  by  a  multi- 
plication of  the  ropes  or  chains  of  the  tackle  through  which  the 
load  is  suspended,  and  partly  by  gearing  within  the  machine, 
which  latter  thus  becomes  an  important  feature  in  crane  work. 
The  gearing  ordinarily  used  for  this  purpose  consists  either  of 
spur  wheels  and  pinions  or  of  worm  wheels  and  worms,  or  both 
combined,  and  the  smoothness  and  economy  of  power  of  the 
machine  depend  largely  upon  the  manner  in  which  the  gearing  is 
made. 


Crane  Details. — Hoisting  Gear.  7  — 

A  second  feature  of  prime  importance  in  the  hoisting  gear  of 
a  crane  is  the  mode  of  sustaining  the  load,  and  guarding  against 
its  "  running  down  "  when  the  application  of  the  motive  power 
is  discontinued.  This  has  heretofore  been  accomplished,  in 
machines  having  spur  gearing,  by  a  ratchet-wheel,  the  pawl  of 
which  has  to  be  entirely  disengaged  to  permit  lowering  to  occur, 
or  by  a  brake,  which,  when  on,  prevents  all  motion  of  the  machine, 
and  which  requires  to  be  held  or  thrown  off,  both  in  hoisting  and 
lowering.  In  machines  having  worm  gearing,  the  end  is  attained 
by  a  construction  of  the  worm  wheels  such  that  the  friction 
between  the  worm  and  the  wheel  is  sufficient  to  prevent  the 
backward  rotation  of  the  worm  under  the  pressure  of  the  teeth 
of  the  worm  wheel  caused  by  the  load,  the  resistance  thus 
generated  sufficing  to  prevent  the  running  down  of  the  load. 

The  worm-wheel  system  is  usually  safe  against  accidents,  but 
is  not  economical  of  power  if  the  worm  gears  are  proportioned, 
as  above  explained,  to  hold  the  load  suspended  without  running 
backwards  when  the  application  of  power  ceases,  as  is  usually  the 
case.  The  spur-wheel  system,  on  the  other  hand,  is  a  constant 
and  inevitable  source  of  great  danger,  both  to  the  load  and  to  the 
operator.  With  the  least  carelessness  in  lowering,  the  load  begins 
to  descend  with  great  velocity,  and  the  mechanism  is  driven 
backwards  with  corresponding  speed  and  violence.  If  not 
checked  the  load  then  practically  falls  as  if  unsupported.  If  too 
suddenly  checked,  violent  strain  is  thrown  upon  the  entire  frame 
of  the  crane  and  on  its  gearing,  which  latter  is  thus  liable  to 
damage,  and  even  to  "  stripping  "  or  fracture,  in  which  event  the 
load  falls.  Where  spur-geared  cranes  are  operated  by  hand  this 
"  running  down "  of  the  load  involves  a  reversing  or  "  flying 
back  "  of  the  cranks,  which  then  frequently  strike  the  men  before 
they  can  escape  beyond  their  reach.  Accidents  of  this  kind, 
resulting  in  injury  to  limbs,  and  even  to  life,  are  constantly 
happening  with  common  cranes,  and  are  reported  almost  daily  in 
the  newspapers. 

It  is  possible,  however,  so  to  proportion  worm  gearing  as  to 
place  it  almost,  if  not  wholly,  upon  a  parity  with  spur  gearing  in 
regard  to  economy  of  power  transmitted,  and,  by  the  use  of  cut 


8  A    Treatise  on  Cranes. 

worm  wheels,  driven  by  turned  worms  or  pinions  (the  teeth  of  the 
wheel  being  formed  by  means  of  a  chasing  hob  or  cutter),  so  to 
construct  worm  gearing  that  it  becomes  the  best  and  most 
convenient  form  of  gearing  for  use  in  crane  mechanism.  It  is 
found  that  gearing  thus  made  will  not  automatically  support  the 
load,  and  that  the  latter,  if  left  suspended,  will  drive  the  worm 
gearing  backward,  but  in  this  case  the  descent  of  the  load  is 
quite  slow,  and  no  perceptible  acceleration  takes  place,  so  that 
the  worm  gears  thus  act  as  a  governor  to  control  the  load.  By 
the  application  of  a  small  brake  to  the  worm-shaft  this  tendency 
is  counteracted,  and,  by  connecting  this  brake  with  the  levers 
which  control  the  motions  of  the  mechanism,  the  brake  is  easily 
made  automatic,  and  thus  securely  holds  the  load  whenever  the 
crane  mechanism  is  at  rest. 

In  all  cranes,  except  those  of  small  size,  provision  should  be 
made  for  one  or  more  changes  of  speed  in  hoisting  and  lowering, 
so  that  the  speed  may  be  varied  according  to  the  load  and  the 
nature  of  the  work  to  be  done.  Cranes  operated  by  power  may 
be  so  constructed  that  the  maximum  load  can  be  lifted  at  the 
quickest  speed ;  but  they  are  usually  so  proportioned  that  this 
can  be  done  only  at  a  slow  speed.  By  this  plan  much  economy 
of  gearing,  space  and  cost  is  effected,  and  the  practical  efficiency 
of  the  crane  for  all  ordinary  uses  is  not  impaired.  The  most 
perfect  construction  is  one  that  permits  a  change  of  speeds  to  be 
made  whether  the  hoisting  gear  is  in  motion  or  at  rest,  and  which 
sustains  the  load  automatically  while  a  change  of  speed  is  being 
made. 

The  hoisting  gear  of  a  crane  should  therefore  attain  the 
following  results,  viz. : 

(i.)  Such  changes  in  direction  and  velocity  of  the  power 
applied  as  will  give  the  desired  motions  to  the  load. 

(2.)  The  accomplishment  of  this  with  a  minimum  loss  of 
power  through  friction. 

(3.)  The  safety,  both  of  the  operator  and  the  load,  under  all 
conditions  ;  to  insure  which  the  load  must  be  always  self-sustained 
and  incapable  of  "  running  down." 


Crane  Details. —  Traverse  Gear.  9— 

(4.)  Capacity  for  changes  of  speed  and  for  convenient 
transition  from  one  of  these  to  another  at  will,  whether  the  gearing 
is  in  motion  or  at  rest,  and  for  the  automatic  support  of  the  load 
during  the  act  of  changing  speeds. 


TRAVERSE    GEAR. 

In  this,  as  in  the  hoisting  gear,  good  design  and  construction 
are  essential  to  economy  of  power,  and  frequently  to  safety 
against  accidents. 

In  some  types  of  rotary  cranes  no  traverse  mechanism  exists, 
except  an  arrangement  of  parts  which  provides  for  the  rotation  of 
the  crane.  In  others,  such  as  jib  and  derrick  cranes,  provision 
must  also  be  made  for  moving  the  truck  or  trolley  horizontally  on 
the  jib,  and  the  same  provision  is  required  for  moving  the  trolley 
of  bridge  and  traveling  cranes  transversely  on  the  bridge.  In  all 
such  cases  a  separate  mechanism,  distinct  from  the  hoisting  gear, 
has  heretofore  been  employed,  and  is  still  sometimes  desirable  or 
convenient.  When  employed,  its  parts  should  be  as  few  and 
simple  as  possible,  and  it  should  be  so  far  independent  of  the 
hoisting  gear  as  to  permit  either  to  be  used  at  any  time  separately 
or  conjointly.  In  power  cranes  provision  should  be  made  for 
accelerating  the  speed  of  the  trolley  travel  whenever  the  nature 
of  the  work  admits  of  it.  The  best  possible  result  is  attained 
when  travel  of  the  trolley  is  effected  without  varying  the  vertical 
position  of  the  load,  and  without  causing  useless  movement  of  the 
hoisting  chain  or  rope  over  the  sheaves  through  which  it  supports 
the  load,  which  movement  would  involve  much  additional  friction, 
and  cause  rapid  wear  of  the  chain  or  rope. 

In  traveling  cranes  a  point  of  great  importance  is  the  paral- 
lelism of  the  bridge  travel  with  the  longitudinal  tracks.  Any 
defect  here  results  in  increased  resistance  to  traction,  and  any 
considerable  error  might  cause  derailment.  In  traveling  cranes, 
as  heretofore  built,  the  use  of  flanged  wheels  has  been  relied 
upon  to  prevent  derailment,  and  the  propulsion  of  the  bridge  has 
been  effected  by  a  transverse  shaft  extending  the  whole  length  of 
the  bridge,  and  connected  by  gearing  with  the  truck-wheels  sup- 


io  A   Treatise  on  Cranes. 

porting  each  end  of  the  bridge,  so  that,  by  revolving  the  shaft, 
the  truck-wheels  would  be  rotated,  and  the  bridge  be  thereby 
propelled,  provided  the  adhesion  between  the  wheels  and  the 
rails  was  sufficient.  In  some  instances,  where  the  adhesion  has 
not  been  sufficient  to  prevent  slipping,  a  cast  iron  rack  has  been 
laid  adjacent  to  the  longitudinal  tracks,  and  extending  their 
whole  length,  and  pinions,  gearing  into  this  rack,  attached  to  the 
axles  of  the  truck-wheels,  so  that  propulsion  is  effected  indepen- 
dently of  the  adhesion  of  the  truck-wheels  to  the  track.  If  the 
load  were  always  central  on  the  bridge,  and  the  motive  power 
always  applied  to  this  shaft  at  the  center  of  its  length,  this  plan 
would  answer  well,  although  it  is  somewhat  clumsy  ;  but  in 
practice  the  load  is  constantly  varying  in  position,  and  the  motive 
power  is  applied  at  one  end  of  the  long  transverse  shaft,  so  that 
torsion  of  the  shaft  induces  a  considerable  variation  in  the  travel 
of  the  opposite  ends  of  the  bridge.  This  error  is  a  constantly 
varying  one,  according  to  the  portion  of  the  load  resting  upon 
each  truck,  as  determined  by  the  position  of  the  trolley,  the  load 
being  never  equally  distributed  between  the  two  trucks  except 
when  it  is  exactly  in  the  center.  It  follows,  therefore,  that  this 
system  of  bridge  travel,  although  operative,  is  radically  defective, 
and  that  its  use  involves  a  constant  loss  of  power  by  needless 
friction,  and  entails  a  proportionate  amount  of  wear  and  tear  of 
rails,  wheels,  and  driving  gear. 

A  better  and  more  simple  method  of  bridge  propulsion  has 
lately  been  introduced,  by  means  of  which  the  longitudinal 
motions  of  the  bridge  are  effected  by  pulling  each  of  its  ends, 
simultaneously  and  at  equal  speed,  in  the  desired  direction.  For 
this  purpose  light  wire  cables  are  used  which,  by  a  very  simple 
and  ingenious  arrangement  of  guide  sheaves,  are  made  to  act  as 
a  "  squaring  device "  to  hold  the  bridge  at  all  times  perpendicu- 
lar, or  square,  to  the  tracks  upon  which  it  travels.  By  this  system 
the  friction  of  traction  is  reduced  to  a  minimum,  and  the  danger 
of  derailment  from  unequal  travel  of  the  opposite  ends  of  the 
bridge  entirely  obviated. 

From  the  above  facts  it  becomes  evident  that  a  perfect  system 
of  bridge  propulsion  must  hold  the  bridge  always  absolutely 


Crane  Details. — Chains  versus  Ropes.          1 1 

square  with  its  tracks,  and  must  propel  the  opposite  ends  of  the 
bridge  in  the  same  direction,  at  the  s>ame  time,  and  at  the  same 
speed,  however  unequally  the  load  may  be  distributed.  It  is 
desirable  also  that,  in  large  cranes  at  least,  provision  be  made 
for  starting  the  bridge  slowly  from  a  state  of  rest,  and  then 
increasing  the  speed,  and  also  for  varying  the  speed  while  the 
bridge  is  in  motion. 


CHAINS  versus  ROPES, 

AND 
CHAIN    WHEELS   VCTSUS   DRUMS. 

In  almost  every  type  of  crane  the  load  is  primarily  carried 
upon  a  flexible  cord  of  some  kind.  This  usually  consists  of  rope, 
either  hemp  or  wire,  or  of  chain.  Each  of  these  has  distinctive 
merits  and  objections. 

Ropes  have  the  advantage  of  being  formed  of  many  parts  or 
fibres,  so  that  no  splicing  or  welding  is  necessary  in  their  manufac- 
ture ;  and  they  thus  have  an  assured  and  practically  uniform 
strength  throughout  their  length. 

Chains,  on  the  contrary,  consist  of  a  series  of  independent 
links,  each  of  which  is  formed  from  a  straight  bar,  and  welded,  so 
that  a  single  imperfect  weld  injures  the  whole,  the  strength  of  a 
chain  being  obviously  limited  by  the  strength  of  its  weakest  link. 
By  care  and  good  workmanship,  however,  this  danger  can  be 
avoided,  in  which  case  the  chain  becomes  as  safe  as  the  rope,  and 
much  more  durable. 

Where  a  rope  is  used,  the  hoisting  gear  must  necessarily  in- 
clude a  d  rum  or  barrel  upon  which  the  rope  is  wound  up  when  hoist- 
ing takes  place.  Chain  may  also  be  thus  wound  up  on  a  barrel, 
and  this  has  heretofore  been  the  common  practice  when  chains 
have  been  employed  in  crane  construction,  and  a  prominent  feature 
in  cranes  of  large  capacity  has  usually  been  a  proportionately  large 
"  winding-barrel  "  to  receive  the  chain.  A  chain,  however,  admits 
of  another  mode  of  construction,  which  consists  in  substituting 
for  the  wide  barrel  or  drum  a  pocketed  "  chain-wheel,"  consisting 


12  A    Treatise  on  Cranes. 

of  a  narrow  wheel  or  sheave,  of  a  width  only  slightly  greater  than 
that  of  the  chain,  and  having  formed  upon  its  periphery  a  series 
of  indentations  or  "pockets,"  exactly  corresponding  in  size  and 
shape  with  the  links  of  the  chain,  so  that  the  chain  and  the  pockets 
fit  together  accurately,  and  slipping  of  the  chain  upon  the  chain 
wheel  becomes  impossible.  It  thus  follows  that  rotation  of  the 
chain  wheel  causes  positive  motion  of  the  chain  at  a  speed  equal 
to  the  circumferential  velocity  of  the  wheel,  in  a  manner  precisely 
similar  to  the  motion  of  a  rack  driven  by  a  pinion,  or  of  one  spur 
wheel  driven  by  another. 

To  be  used  in  this  way,  it  is  necessary  that  the  chain  should 
have  a  constant  and  uniform  "pitch,"  that  is,  that  every  link 
should  be  exactly  alike,  so  that  the  distance  from  link  to  link  shall 
be  always  the  same  (just  as  in  spur  gearing  the  spacing,  or  pitch, 
of  the  teeth  must  be  uniform),  and  also  that  the  pitch  or  spacing 
of  the  pockets  of  the  chain  wheel  correspond  accurately  with  the 
pitch  of  the  chain.  If  this  be  done,  and  if  the  chain  have  a  cross 
section  of  such  area  that,  when  carrying  the  full  load,  it  is  not 
strained  to  its  elastic  limit,  or  to  a  degree  which  will  cause  any 
permanent  elongation  of  its  links,  then  a  chain  may  be  thus  used, 
in  engagement  with  a  pocketed  chain  wheel,  as  well  and  as  safely 
as  on  a  barrel.  Indeed,  a  properly  shaped  wheel  of  this  kind  is 
much  easier  on  the  chain  than  a  winding  barrel  or  drum,  for  the 
reason  that  the  latter  has  a  cylindrical  surface,  while  the  bearing 
face  of  the  former  is  not  cylindrical,  but  polygonal,  the  bed  or 
bottom  of  each  pocket  being  tangential  to  the  radius  at  its  centre, 
and  so  presenting  a  flat  surface  for  the  parallel  sides  of  each 
alternate  link  to  bear  upon.  When  the  chain  is  wrapped  upon  a 
cylindrical  barrel,  on  the  other  hand,  the  straight  sides  of  every 
alternate  link,  being  tangential  to  the  surface  of  the  barrel,  can 
each  touch  it  at  one  point  only,  the  link  being  unsupported 
throughout  the  rest  of  its  length,,  and  the  tendency  of  the  strain 
induced  by  the  load  is  to  bend  each  of  these  links  to  the  contour 
of  the  barrel.  This  effect  may  be  easily  seen  in  any  chain  which 
has  been  wrapped,  under  severe  strain,  upon  a  cylindrical  barrel, 
unless  the  diameter  of  the  barrel  be  very  large.  The  spriral 
grooving  of  a  barrel  does  not  remedy  this  fault,  although  it  affords 


Crane  Details. — Chain  Wheels  versus  Drums.    13 

a  much  better  bearing  for  the  chain  than  a  plain  cylinder,  which 
latter  is  only  permissible  for  small  chains  and  light  loads. 

For  heavy  cranes  hemp  ropes  are  rarely  used  owing  to  the 
size  and  multiplicity  of  parts  required,  and  to  their  rapid  wear. 
They  are  also  inadmissible  where  liable  to  be  exposed  to  much 
heat  as,  for  instance,  in  a  foundry.  Wire  ropes  are  more 
available,  and  are  often  employed,  but  these  also  wear  rapidly 
unless  the  sheaves  and  barrels  around  which  they  pass  are  of 
large  diameter,  while  this  requirement,  if  met,  reduces  the 
effective  height  of  hoist  and  necessitates  more  parts  or  gearing  to 
obtain  the  necessary  purchase,  and  augments  the  bulkiness  of  the 
machine.  Either  material  involves  resort  to  a  large  winding 
barrel  or  drum. 

The  usual  and  best  device  for  large  cranes  is  well  made  chain, 
and  this,  when  used  with  pocketed  chain  wheels  and  sheaves, 
gives  the  best  and  most  satisfactory  results,  and  leaves  nothing  to 
be  desired.  The  adoption  of  this  plan  dispenses  with  winding 
barrels,  preserves  the  shape,  and  therefore  the  durability,  of  the 
links  of  the  chain,  and  in  every  way  simplifies  and  compacts  the 
mechanism. 

The  relative  merits  of  the  several  systems  may  now  be 
summed  up  as  follows  : 


(i.)  As  to  the  Sustaining  Cord. 

Hemp  Ropes. — Admissible  only  for  small  cranes  not  in 
frequent  use  and  not  exposed  to  the  weather  or  to  heat. 

Wire  Ropes. — Available  under  any  ordinary  conditions,  but 
involving  a  winding  barrel  of  large  diameter  and  large  sheaves  ; 
not  economical  of  space. 

Chains. — Possessing,  if  well  made,  all  advantages  and  the 
greatest  durability  :  common  chain,  requiring  a  winding  drum,  but 
permitting  it  and  the  sheaves  to  be  of  smaller  diameter  than  with 
wire  rope ;  pitch  chain,  dispensing  with  a  drum  and  admitting  of 
the  use  of  a  narrow  chain  wheel. 


14  A    Treatise  on  Cranes. 

(2.)    As  to  the  Winding  Device  for  Hauling  in  and  Paying  Out 
the  Rope  or  Chain. 

Winding  Drums  or  Barrels. — These  must  have  a  diameter 
and  length  such  as  will  enable  them  to  receive  the  whole  length 
of  rope  or  chain  to  be  hauled  in  by  winding  it  upon  their  surface 
in  one  coil,  without  overlapping.  In  large  cranes  the  load  is 
usually  carried  upon  four,  six,  or  even  eight  parts  of  rope  or 
chain,  so  that  the  length  to  be  wound  up  amounts  to  four,  six,  or 
eight  times  the  effective  hoist,  and  the  dimensions  of  the  barrel 
thus  become  very  large.  Moreover,  this  barrel  must  either  be 
caused  to  travel  longitudinally  on  its  shaft,  so  that  the  rope  or 
chain  as  it  leads  off  shall  be  always  in  the  center  of  the  crane  and 
hoisting  mechanism  (which  method  of  construction  involves 
serious  complication  and  greatly  widens  the  space  occupied  by 
the  gearing),  or  the  rope  or  chain,  as  it  uncoils,  be  permitted  to 
vary  in  position  from  one  end  to  the  other  of  the  barrel,  in  which 
case  it  is  nearly  always  out  of  center,  thus  inducing  objectionable 
lateral  strains  and  causing  greater  friction  and  wear. 

Chain  Wheels,  with  Pockets. — These  require  a  width  only 
slightly  greater  than  a  single  part  of  the  chain,  and  a  diameter 
merely  sufficient  to  give  the  proper  engagement  with  it,  so  that 
both  dimensions  become  much  smaller  than  in  a  winding  barrel, 
and  the  total  space  occupied  is  but  a  small  fraction  of  that  required 
for  the  latter  device.  The  chain  wheel  is  fixed  in  direct  line  with 
the  chain,  and  all  lateral  strains  are  avoided,  while  the  flat 
bearings  afforded  for  the  chain  by  the  pockets  preserve  the  shape 
of  the  links  and  protect  them  from  bending  strains.  The  slack 
chain,  after  passing  over  the  wheel,  falls  into  a  proper  receptacle 
below. 

From  this  analysis  of  the  facts  is  deduced  the  proposition  that 
chains,  if  well  made,  constitute  the  best  form  of  flexible  cord  for 
sustaining  the  load  in  a  crane,  and  that  a  well  constructed  chain 
wheel  (as  contradistinguished  from  a  winding  barrel)  is  the  best 
form  of  device  for  hauling  in  and  paying  out  the  chain  ;  and 
therefore,  that  the  best  method  of  crane  construction  involves  the 
use  of  these  two  elements. 


Crane  Details. —  Trolleys  and  Trucks.          15 


TROLLEYS    AND    TRUCKS. 

The  trolley  of  a  crane  is  the  movable  carriage  from  which 
the  load  is  immediately  suspended  and  by  which  longitudinal 
motion  of  the  load  upon  the  jib,  or  the  bridge,  of  a  crane  is 
effected.  The  term  truck  is  usually  restricted  to  the  wheeled 
carriage  used  to  support  each  end  of  the  bridge  of  a  traveling 
crane,  or  the  corresponding  part  of  rectilinear  cranes  of  all  kinds. 
Rectilinear  cranes  require  usually  at  least  one  trolley,  and  one  or 
more  trucks.  Rotary  cranes  require  usually  a  trolley  only. 

The  whole  load  of  a  crane  is  hung  primarily  upon  the  trolley, 
and  where  trucks  are  used,  is  transferred  in  full  to  them,  together 
with  the  weight  of  the  crane  itself.  It  is  desirable,  therefore,  that 
these  parts  should  not  only  possess  ample  strength  to  resist  the 
strains  they  may  be  subjected  to,  but  also  that  they  be  so  arranged 
that  any  yielding  or  breakage  of  their  parts  will  not  allow  the  load 
to  fall  to  the  ground,  but  only  permit  it  to  descend  until  the 
supporting  beam  rests  on  the  rails  upon  which  the  trolley  or  truck 
is  to  travel.  For  this  reason  the  construction  should  be  such  that 
the  ends  of  the  bridge,  in  traveling  and  similar  cranes,  overlap 
the  longitudinal  tracks,  and  the  axles  or  housings  of  the  trolley, 
in  cranes  of  all  kinds,  overlap  the  rails  upon  which  it  runs.  It  is 
further  desirable  that  the  vertical  distance  between  these  over- 
lapping parts  and  the  rails  be  as  small  as  possible,  so  that,  in  the 
event  of  any  break  occurring,  the  distance  through  which  these 
parts  pass  before  being  arrested  is  so  small  that  no  serious 
shock  can  ensue.  With  careful  designing  this  distance  can  be 
reduced  to  merely  the  necessary  clearance  of  the  parts,  which 
need  not  exceed  more  than  one  inch  or  less. 

A  natural  preference  exists  for  wrought  iron  rather  than  cast 
iron  as  the  material  from  which  to  construct  the  moving  parts  of 
a  crane  ;  and,  unquestionably,  it  is  always  best  to  use  wrought 
iron  for  parts  that  are  to  be  exposed  to  tension  under  heavy  loads. 
Cast  iron,  however,  is  the  better  material  for  those  parts  that  are 
subject  to  compression,  and  by  skillful  designing  it  is  usually 
possible  so  to  arrange  the  parts  of  trolleys  and  trucks  as  to  use 
cast  iron  wherever  stiffness  or  resistance  to  compression  is 


1 6  A    Treatise  on  Cranes. 

required,  while  still  employing  wrought  iron  for  the  parts  under 
tension.  In  this  way  the  greatest  economy  is  attained,  and  not 
unfrequently  a  better  result  secured  than  by  the  use  of  either 
material  alone. 

The  wheels,  both  of  trolleys  and  trucks,  should  be  true 
cylindrically,  should  be  double-flanged,  and,  by  preference,  should 
have  chilled  treads.  If  wheels  of  small  diameter  are  used,  in 
order  to  economize  height,  they  should  be  provided  with  anti- 
friction bushings,  to  counteract  the  increased  resistance  to  traction 
caused  by  their  small  diameter.  The  wheel-base,  or  distance  from 
center  to  center  of  the  adjacent  wheels,  should  be  as  large  as 
possible,  in  order  to  avoid  cramping  between  the  rails,  and  to 
facilitate  the  easy  motion  of  the  carriage  upon  its  track.  In  large 
traveling  cranes  it  is  desirable  that  the  axles  of  the  truck-wheels 
be  supported  in  spherical  bearings,  so  that  the  wheels  may  adjust 
themselves  to  any  yielding  of  the  track  which  may  result  from  the 
passage  of  heavy  loads,  and  thus  all  unnecessary  straining  of  the 
parts  of  the  truck  be  avoided. 

FRAMES    AND    GIRDERS. 

In  the  early  building  of  cranes,  timber  was  chiefly  used  in 
the  construction  of  their  frame-work,  and  is  still  much  employed 
in  this  country.  Improvements  in  the  manufacture  of  structural 
irons,  and  the  large  variety  of  shapes  now  obtainable,  have, 
however,  greatly  altered  the  relative  cost  of  construction  in  timber 
and  iron,  and  made  it  possible  to  employ  iron  much  more  largely 
than  formerly. 

Experience  in  the  practical  designing  and  building  of  cranes 
of  many  types  has  convinced  the  writer  that,  by  the  proper  use  of 
materials,  crane  construction  in  iron  costs,  in  most  cases,  little,  if 
any  more  than  in  wood.  For  example  :  The  frame  of  an  ordinary 
jib  crane  consists  of  three  principal  members — the  mast,  the  jib, 
and  the  brace.  If  of  iron,  each  of  these  consists  of  a  single  piece 
or  bar,  or,  in  larger  cranes,  of  two  parallel  pieces,  and  the  union  of 
these  several  members  at  their  intersections  is  accomplished  simply 
and  very  economically.  If  timber  be  used,  on  the  other  hand, 


Crane  Details. — Frames  and  Girders.          i  7 

more  or  less  trussing  is  required,  except  for  small  cranes  ;  and 
many  bolts,  washers  and  castings  are  necessary  to  provide  for  the 
proper  bearing  of  one  part  upon  the  other  and  to  securely  fasten 
the  several  parts  together.  The  iron  frame  when  once  properly 
put  together  is  practically  imperishable.  If  properly  painted  it 
will  not  deteriorate,  nor  is  it  affected  by  exposure  to  the  weather 
or  by  extremes  of  heat  and  cold.  A  timber  frame,  on  the  contrary, 
is  liable  to  decay,  which  is  hastened  by  exposure  to  the  weather, 
and  it  is  unfavorably  affected  by  heat.  More  or  less  shrinkage  of 
the  timber  always  occurs,  thereby  relaxing  the  engagement  of  the 
several  parts  and  disturbing  the  relations  of  the  bearings  which 
receive  the  strains  caused  by  the  load.  The  result  of  these 
changes  in  a  timber  frame  is  to  permit  more  or  less  working  of 
the  parts  one  upon  the  other.  This  tends  to  augment  the  trouble 
from  which  it  arises,  and  as  a  result  the  safety  of  the  crane  is 
lessened  and  its  durability  continually  impaired. 

So  also  in  the  bridges  of  traveling  cranes.  If  the  span  be  great, 
construction  in  timber  involves  much  splicing,  and  this  in  turn 
necessitates  unnecessary  material  in  many  places.  The  trussing 
and  bolting  requires  a  considerable  amount  of  iron  work,  and 
usually  necessitates  a  deeper  girder  than  is  required  in  iron,  thus 
lessening  the  available  head-room  beneath  the  crane.  It  is  believed 
that  an  accurate  comparison  of  the  relative  costs  of  crane  frames  or 
girders  built  in  wood  and  in  iron,  if  proportioned  with  an  equal 
factor  of  safety  throughout,  would  show  little  if  any  economy  of 
first  cost  in  favor  of  wood. 

The  availability  of  iron  for  structures  of  this  kind  has  been 
greatly  increased  by  the  ability  of  the  mills  to  produce  extreme 
lengths  when  required.  No  difficulty  is  now  experienced  in  this 
country  in  obtaining  the  heaviest  channel  and  I-beams  in  lengths 
of  50  feet  or  more,  and  the  largest  angle  irons  are  also  obtainable 
in  single  lengths  of  80  or  90  feet.  It  thus  becomes  possible  to 
form  each  of  the  principal  members  of  cranes  of  a  single  con- 
tinuous iron,  the  advantages  of  which  are  too  obvious  to  need  de- 
scription. 

It  will  be  conceded  that  iron  frames  and  girders  are  much  to 
be  preferred  for  every  reason,  with  the  single  exception  of  possible 


1 8  A    Treatise  on  Cranes. 

economy  of  first  cost.  Taking  into  account,  however,  all  of  the 
conditions  and  considerations  above  mentioned,  it  is  believed  that 
the  difference  in  first  cost  is  so  slight — in  many  cases  not  appre- 
ciable— that  the  frames  and  girders  of  cranes  of  all,  except  perhaps 
the  smaller  kinds,  should  now  be  built  entirely  of  iron. 

In  conclusion,  it  may  be  hoped  that  the  foregoing  analysis 
will  conduce  to  a  clearer  understanding  of  cranes,  both  as  regards 
their  various  forms  or  types,  and  the  more  important  details  of 
their  construction.  The  tendency  of  the  day  in  all  directions  is 
toward  the  specializing  of  products;  that  is,  the  concentration  of 
the  abilities  and  resources  of  individual  establishments  upon  the 
development  of  certain  distinct  or  special  products.  Consumers 
are  the  ones  most  benefited  by  this  condition  of  things,  since  it 
enables  them  to  procure  products  of  higher  quality  and  ultimately 
at  a  lessened  cost.  Where  such  specialists  exist,  the  best  result 
is  usually  attained  by  submitting  to  them  a  clear  statement  of  the 
work  to  be  done  and  of  the  surrounding  conditions,  and  by  accept- 
ing the  advice  thus  obtained  as  to  the  type  or  form  of  machine 
best  adapted  to  meet  the  special  requirements  of  the  case. 


PART   II. 


PART    II. 


INTRODUCTION. 


The  contents  of  this  Part  comprise  a  full  description  of  each 
of  the  more  important  details  entering  into  the  construction  of  the 
Weston  Cranes,  together  with  reproductions  of  many  of  the 
working  drawings  of  the  same. 

In  these  days  of  keen  competition  it  is  not  usual  to  make 
such  an  unreserved  exhibit  of  the  details  which  form  the  founda- 
tion of  a  successful  business.  If  such  information  is  published,  it 
cannot  be  expected  that  interested  competitors  will  not  avail  of  it 
to  further  their  own  interests  so  far  as  they  conveniently  or  legally 
may.  It  has  been  the  policy,  however,  of  the  builders  of  the 
Cranes  herein  described  to  carefully  and  thoroughly  protect  their 
inventions  and  improvements  by  patent,  and  they  are  thus  enabled 
to  publish  the  results  of  their  work  with  knowledge  that  its  bene- 
fits are  legally  secured  to  them,  and  with  confidence  that  their 
legal  rights  will  be  cheerfully  respected  without  resort  on  their 
part  to  litigation  for  their  enforcement.  For  further  information 
on  this  point  those  interested  are  referred  to  the  last  page  of 
Part  II. 

In  describing  the  several  details  of  crane  construction,  the 
author's  effort  has  been  to  illustrate  the  important  principles  of 
action  which  they  embody,  rather  than  to  describe  the  precise 
forms  and  constructions  actually  used.  The  latter  necessarily 
vary  somewhat  in  each  type  of  crane  in  which  any  particular 
device  is  employed.  The  principle  and  mode  of  action  of  the 
various  devices  will,  it  is  hoped,  be  made  clear  to  the  reader  in 
the  following  pages,  and  the  experience  and  facilities  of  the 
builders  are  a  guaranty  that  the  various  adaptations  are  in  each 
case  properly  made. 


22  A    Treatise  on   Cranes. 


CRANE   DETAILS. 

Certain  elements  are  found  to  be  common  to  numerous  types 
of  cranes,  and  it  will  conduce  to  clearness  and  brevity  of  state- 
ment in  Part  III,  which  is  devoted  to  descriptions  of  complete 
cranes,  to  describe  these  elementary  parts  and  devices  separately, 
in  advance,  rather  than  under  the  head  of  each  kind  of  crane  in 
which  they  occur.  The  following  details  employed  in  the  Weston 
Cranes  wilt  therefore  be  thus  described,  viz.  : 

CHAINS  ; 

CHAIN  WHEELS  ; 

SPUR  GEARING  ; 

WORM  GEARING  ; 

FRICTIONAL  SAFETY  RATCHET  ; 

CLUTCHES ; 

BRIDGE  SQUARING  DEVICE  ; 

BRIDGE  MOVING  DEVICE  ; 

BRIDGE  AND  TROLLEY  MOVING  DEVICE  ; 

TROLLEY  TRAVELING  MECHANISM  ; 

GEARING  OF  JIB  CRANES  ; 

GEARING  OF  TRAVELING  CRANES  ; 

BRIDGE  TRUCKS  ; 

FRAMES  AND  GIRDERS  ; 

BRIDGES  AND  TRESTLES  ; 

POWER  TRANSMISSION  ; 

TAKE-UPS; 

HOOKS  ; 

BLOCKS  AND  BUSHINGS  ; 

FOUNDATIONS. 


Crane  Details. — Chains.  23 


CHAINS. 

The  Chain  Wheel  system  having  been  adopted  by  reason  of 
the  advantages  it  affords,  as  explained  in  Part  I,  the  procure- 
ment of  a  true  pitch  chain  becomes  a  necessity. 

The  same  necessity  exists  in  the  Weston  Differential  Pulley 
Blocks,  and  the  present  makers  of  the  latter,  upon  undertaking 
their  manufacture  in  1875,  were  compelled  to  devise  and  adopt  a 
process  of  chain  making  which  would  insure  the  production  of  a 
chain  of  perfectly  uniform  pitch.  To  insure  this  result,  a  shop  for 
chain  making  was  erected  and  equipped  with  the  best  appliances, 
and  the  necessary  skilled  labor  procured.  Chain  making  is  one  of 
the  few  remaining  manual  trades  in  which  modern  machinery  has 
not  to  a  greater  or  less  extent  displaced  the  skill  of  the  individual 
workman.  Many  attempts  have  been  made  to  produce  chains  by 
machinery,  and  although  some  success  has  been  attained,  no 
machine-made  chain  has  yet  been  produced  having  sufficient 
reliability  and  uniformity  of  quality  to  adapt  it  to  use  in  cranes. 
The  all-important  operation  in  chain  making  is  the  process  of 
welding  the  links,  and  in  this  the  personal  element  seems  indis- 
pensable to  a  perfect  result,  no  machine,  however  perfect,  taking 
the  place  of  the  skill  and  intelligence  of  the  workman. 

As  used  in  the  Weston  Cranes,  the  pitch  chains  of  the  smaller 
sizes  are  made  entirely  of  Norway  iron,  while  for  the  larger  sizes 
either  Norway  iron  or  American  iron  of  high  elasticity  and 
ductility,  is  used.  Each  link  is  forged  and  welded  with  great 
care,  and  much  more  time  and  labor  is  expended  on  this  part  of 
the  work  than  is  the  case  with  common  chain.  All  of  this  pitch 
chain  is  made  under  a  patented  process,  which  consists  in  forging 
the  chain  slightly  under  pitch,  after  which  it  is  first  cleaned  and 
brightened  by  "rattling,"  and  then  stretched  in  a  special  machine 
to  the  final  gauge  or  pitch.  The  first  process  causes  the  several 
links  to  come  into  more  perfect  contact  or  bearing  by  removing 
the  scale  and  other  slight  asperities  from  their  surfaces.  The 


A    Treatise  on  Cranes. 


second  process  assists  in  bringing  their  adjacent  surfaces  into 
closer  contact,  tends  to  straighten  the  sides  of  the  links,  and  gives 
the  iron  a  slight  initial  set  by  straining  it  to  a  degree  somewhat 
greater  than  that  which  will  be  caused  by  the  load  which  it  is 
intended  to  carry.  The  final  step  in  the  process  is  a  careful  and 
rigid  inspection  of  each  link  of  the  chain  and  the  removal  of  any 
which  are  at  all  imperfect.  As  a  result  of  this  treatment,  a  chain 
is  obtained  which  is  accurately  uniform  in  pitch,  and  which,  when 
used  within  the  intended  limit  of  load,  will  not  stretch  or  alter  its 
pitch.  It  is  believed  that  the  chain  thus  produced  is  more  perfect 
and  reliable  than  any  made  heretofore  or  elsewhere. 

In  determining  the  diameter  of  iron  for  the  several  sizes  of 
chain,  those  sizes  have  been  adopted  which  will  limit  the  stress 
upon  the  links  of  the  chain  to  a  maximum  of  from  9,000  to  10,000 
pounds  per  square  inch  of  cross-section  when  carrying  the  full 
load.  As  the  pitch  chain  was  designed  primarily  for  use  in  the 
Weston  Differential  Pulley  Blocks,  in  which  the  load  is  always 
carried  upon  two  parts  of  chain,  the  nominal  capacity  of  the 
several  sizes  indicates  in  each  case  the  maximum  load  intended 
to  be  carried  upon  two  parts  of  the  chain.  A  single  part  is,  of 
course,  capable  of  carrying  a  load  of  one-half  the  amount  given 
in  the  table. 

The  following  table  gives  the  dimensions  of  the  several  sizes 
of  the  pitch  chain  above  described. 


Nominal  capacity  in  Tons*  

U 

U 

1 

\% 

9 

fl 

4 

5 

6 

8 

10 

Diameter  of  Iron  in  inches  

T3« 

J4 

A 

re 

% 

rV 

K 

A 

% 

ii 

« 

*  The  upper  line  indicates  the  load  which  can  be  safely  carried  on  two  parts  of  the 
chain,  i.e..  as  used  in  a  one-sheave  tackle  block.  Each  part  of  the  chain  thus  carries 
one-half  of  the  total  load.  If  the  load  is  to  be  carried  by  a  single  chain,  select  a  chain 
of  a  nominal  capacity  of  twice  the  intended  load. 


Crane  Details. — Chain  Wheels.  25 


CHAIN  WHEELS. 

Having  provided  a  perfect  pitch  chain,  the  next  essential  is 
a  chain  wheel  to  drive  it.  This  wheel  must  have  pockets  for 
the  links  of  the  chain  to  engage  with,  the  pitch  of  which,  or  their 
circumferential  distance  from  center  to  center,  must  coincide 
accurately  with  the  pitch  of  the  chain.  The  shapes  of  the  several 
portions  of  these  pockets  are  also  matters  of  great  importance 
and  nicety.  The  bottom  of  each  is  tangential  to  the  radius,  thus 
giving  a  flat  bearing  for  each  link;  the  center  is  grooved  to  clear 
the  links  which  present  themselves  on  edge ;  and  the  teeth  or 
shoulders  between  the  pockets,  by  which  the  work  of  driving  is 
done,  are  made  as  thick  as  possible,  to  resist  the  severe  strains 
that  come  upon  them,  and  yet  are  so  curved  on  their  two  faces 
that  the  links,  when  entering,  shall  do  so  without  strain  or  jar, 
and  shall  pass  off  again  without  clinging. 

The  exact  shape  of  these  teeth  has  been  determined,  partly 
by  careful  plotting,  and  partly  by  experiment,  the  experience 
acquired  in  the  manufacture  of  the  Weston  Pulley  Block,  in 
which  similar  chain  wheels  are  used,  having  greatly  assisted  in 
the  determination. 

The  best  material  for  the  chain  wheel  has  been  found,  by 
experience,  to  be  soft  cast  iron,  as  this  causes  the  least  wear  upon 
the  chain,  and  as  it  is  of  course  best  to  have  the  wear  come 
upon  the  wheel  (which  is  easily  and  cheaply  replaced)  than  upon 
the  chain.  In  all  of  the  several  types  of  cranes  hereinafter 
described  the  chain  wheels  are  made  and  inserted  so  as  to  be 
easily  replaced.  This,  however,  does  not  require  to  be  frequently 
done,  as  the  wheels  will  usually  endure  five  or  six  years  of  con- 
stant use  before  wearing  out. 

To  further  insure  the  proper  engagement  of  the  chain 
wheel  and  chain,  a  chain  guide  is  provided  as  shown  in  Fig.  i. 

The  functions  of  this  chain  guide  are  :  — 

(i) — To  cause  the  chain  to  enter  properly  into  engagement 
with  the  wheel ; 


26 


A    Treatise  on  Cranes. 


(2) — To  hold  it  in  engagement  with  several  of  the  pockets  of 
the  wheel,  so  that  the  strain  upon  the  chain  is  distributed  over 
these  several  pockets,  and  "stripping"  of  the  wheel  prevented; 
and 

(3) — To  permit  the  lower  half  of  the  wheel  to  be  used  for 
engagement  with  the  chain  and  yet  cause  the  slack  side  of  the 
chain  to  follow  the  wheel  up  to  the  horizontal  center  line  again. 


FIG.  i.— Chain  Wheel,  Guide  and  Stripper. 

The  construction  by  which  these  results  are  obtained  is 
clearly  illustrated  in  the  cut,  in  which  A  represents  a  pocketed 
chain  wheel  mounted  upon  the  plate  or  frame  B.  C  is  the  "  chain 
guide,"  enveloping  the  lower  half  of  the  chain  wheel  A,  and 
bolted  securely  to  the  plate  B.  The  inner  curved  surface  of  the 
chain  guide  is  grooved,  and  is  of  such  shape  as  to  leave  a  space 
between  it  and  the  periphery  of  the  chain  wheel  merely  sufficient 
to  admit  the  chain.  The  latter  is  thus  compelled  to  enter  pro- 
perly, and  is  held  securely  in  engagement  with  the  pocketed 
chain  wheel  throughout  the  arc  of  contact.  At  E  the  chain 
guide  carries  a  small  roller,  over  which  the  slack  chain  passes 
downward  into  a  suitable  box  or  receptacle. 

To  insure  the  proper  separation  of  the  chain  from  the  chain 


Crane  Details.- — Chain  Wheels.  27 

wheel  at  the  point  of  disengagement  there  is  provided  a  "  chain 
stripper."  This  piece,  marked  D  in  the  cut,  is  also  bolted  to  the 
plate  B,  and  is  provided  with  a  projecting  tongue  or  rib  D',  the 
point  of  which  lies  deep  in  the  center  groove  of  the  wheel,  and 
thus  strips  or  separates  the  chain  from  the  wheel  as  it  reaches 
the  proper  point,  and  prevents  any  clinging  of  the  chain  to  the 
wheel.  A  prolongation  of  the  "stripper"  D  covers  the  guide 
sheave  at  E  and  insures  the  proper  passing  downward  of  the 
chain. 

The  construction  of  the  chain  wheel  and  its  adjuncts,  which 
is  above  illustrated  and  described,  constitutes  a  perfect  device 
for  hauling  in  and  paying  out  chain,  whether  fully  loaded  or 
empty,  and  is  moreover  easier  upon  the  chain,  and  more  con- 
ducive to  its  endurance,  than  any  ordinary  form  of  winding  bar- 
rel or  drum.  With  slight  modifications,  to  adapt  it  to  the  varying 
conditions,  this  construction  is  embodied  in  all  of  the  various 
types  of  the  Weston  Cranes. 


28 


A    Treatise  on  Cranes. 


SPUR    GEARING. 


The  proper  action  of  many  of  the  mechanisms  employed  in 
crane  construction  depends  largely  upon  the  character  of  the 
spur  wheels  used  in  effecting  the  necessary  changes  of  speed  and 
motion. 


FIG.  2.— Teeth  of  Spur  Wheels. 

In  all  of  the  Weston  Cranes  which  are  operated  by  power, 
cut  gears  are  used  throughout.  The  rims  of  these  wheels  are  cast 
solid  and  turned,  after  which  the  teeth  are  formed  in  a  gear- 
cutting  engine  by  means  of  suitable  mills  or  cutters.  The  char- 
acter of  the  work  obtained  in  this  way  depends  chiefly  upon  the 
shape  or  contour  of  the  cutters  by  which  the  teeth  are  formed. 
The  Pratt  &  Whitney  Co.,  of  Hartford,  Conn.,  have  given  this 
subject  the  most  exhaustive  consideration,  and  have  at  great 
expense  developed  a  system  of  producing  cutters  for  gears  which 


Crane  Details. — Spur  Gearing.  29 

are  believed  to  be  more  perfect  than  any  heretofore  made. 
These  cutters  are  used  exclusively  in  the  production  of  cut  gears 
for  the  Weston  Cranes. 

The  spur  gears  for  cranes  of  the  smaller  sizes,  and  for  operation 
by  hand,  are  usually  cast,  not  cut.  These  castings,  however,  are 
made  from  metal  patterns,  in  forming  the  teeth  of  which  latter 
the  same  kind  of  cutters  are  used  ;  so  that  the  cast  gearing  is 
relatively  as  good,  in  the  essential  matter  of  the  contour  of  teeth, 
as  is  the  cut  gearing  above  referred  to. 

The  general  appearance  of  this  gearing,  and  the  shape  of  the 
teeth,  is  illustrated  by  Fig.  2. 


A    Treatise  on  Cranes. 


WORM    GEARING. 

For  the  reasons  stated  under  the  head  of  <:  Hoisting  Gear/ 
in  Part  I,  many  advantages  accrue  from  the  use  of  worm  gearing 
in  the  construction  of  hoisting  machinery.  Among  these  may  be 
mentioned  its  compactness  as  compared  with  spur  gearing,  the 
ability  to  operate  shafts  at  right  angles  to  each  other  without 
resort  to  bevel  gears,  and  great  facility  in  the  application  of 
automatic  brakes  where  necessary.  In  well  proportioned  worm 
gearing  with  cut  teeth,  friction  cannot  be  relied  upon  to  hold  a 
suspended  load  from  running  down,  but  a  very  moderate  brake 
resistance  applied  to  the  worm  shaft  will  accomplish  this  result. 
If  a  load  suspended  through  a  train  of  spur  gearing  be  allowed 
to  run  down,  it  will  do  so  at  an  accelerating  velocity  approximat- 
ing to  that  of  a  falling  body.  With  worm  gearing,  however,  very 
little  acceleration  takes  place  after  a  certain  speed  has  been 
attained,  and  gearing  of  this  kind  thus  becomes  a  safety  device 
which  prevents  undue  acceleration  of  the  load  even  when  running 
free,  and  is  a  most  valuable  means  of  preventing  accidents,  both 
to  the  mechanism  and  to  those  operating  it. 

The  subject  of  worm  gearing  was  very  carefully  investigated 
by  the  late  Mr.  Robert  Briggs,  C.  E.,  and  the  following  description 
of  the  correct  method  of  construction,  condensed  from  a  paper 
by  him,*  fully  describes  the  system  employed  in  the  worm-gearing 
used  in  the  Weston  Cranes. 

There  is  a  current  opinion  among  machinists  in  general  that 
worm  gearing  offers  so  disastrous  a  frictional  resistance  in  wear, 
that  its  use,  except  for  purposes  where  little  power  is  to  be  .trans- 
mitted, and  where  certain  slow  movements  are  to  be  effected,  is 
not  permissible  in  good  mechanism.  This  view  is  supported  by 
most  of  the  text-books,  which  invariably  represent  the  laying  out 

*1Vorm  Gearing,  by  Robert  Briggs,  C.  E.  ;  Mechanics^  Vol.  i,  No.  12,  March  25.  1882, 
New  York.  See  also  Unwin's  "Elements  of  Machine  Design,"  Fourth  Edition,  London, 
1882,  pr.ge  499,  et  seq. 


Crane  Details. —  Worm  Gearing.  31 

of  the  teeth  by  considering  the  worm  as  a  rack  with  inclined  teeth 
where  the  pitch-lines  of  the  worm  and  wheel  are  taken  on  a  plane 
passing  through  the  axis  of  the  worm. 

Now,  the  fact  is  that  the  use  of  worm  gearing  for  hoists, 
cranes,  boring-bars,  lathes,  etc.,  has  been  growing  in  favor,  and  it 
is  found  that  neither  excessive  loss  of  power,  nor  excessive  wear 
of  gearing  ensues.  In  regard  to  friction,  it  is  established  that  for 
the  ordinary  ratio  of  wheel  to  worm,  say,  not  to  exceed  60  or  80 
to  i,  well  fitted  worm  gear  will  transmit  motion  backward  through 
the  worm,  exhibiting  a  lower  co-efficient  of  friction  than  is  found 
in  any  other  description  of  running  machinery. 

In  order  to  reach  this  result  the  following  method  of  laying 
out  a  worm  gear  and  worm  is  employed.  Assume  the  teeth  on 
the  worm  to  be  0.65  of  the  pitch  radially,  of  which  0.60  P  is  to  be 
the  line  of  contact  with  the  teeth  of  the  wheel  (on  the  radius  and 
also  on  the  plane  through  the  middle  of  the  teeth),  and  that  0.05 
P  be  for  clearances  between  the  roots  and  points  of  worm  and 
wheel  teeth.  Let  the  teeth  of  the  wheel  follow  the  circle  of  the 
worm  throughout  the  arc,  which  ought  not  to  exceed  60°.  Let 
R  =  outside  radius  of  worm  ;  Rp  =  radius  of  pitch  of  worm  ;  F 
=  face  of  wheel  at  root  of  teeth  ;  and  P  =  pitch  of  teeth  ;  then 

Rp  =  %  \  R  +  (R  _  0.6  P)  Cos  a  \ 

F  =  2  (R  +  0.05  P)Sin  a. 

To  simplify  the  process  of  laying  out  worm-wheels  it  has 
been  usual  to  make  the  outside  radius  of  the  worm  R  =  2  P,  and 
the  angle  a  =  60°,  when 

Rp  =  i. 606  P,  and  F  =  2.05  P. 

The  effect  of  this  method  of  setting  out  pitch-lines  for  the 
teeth  of  screw  gearing  is  to  bring  the  bearing,  or  working  lines 
of  contact,  for  both  orders  of  teeth  more  nearly  on  the  true  pitch- 
line,  and  not  to  throw  much  effort  or  work  on  the  points  of  the 
teeth  of  the  worm  wheel  outside  of  the  true  pitch-line. 


32  A    Treatise  on  Cranes. 

The  following  illustration  represents  a  worm  wheel  and 
worm  constructed  in  accordance  with  the  above  system  and  of 
the  proportions  employed  in  the  Weston  Cranes. 


1 1. 'Plan  of  Root  of  Tooth 
K~K.  Section  on  Pitch  Line  X  Y 


FIG.  3.— Worm  Wheel  and  Worm. 


Crane  Details — Frictional  Safety  Ratchet.     33- 


FRICTIONAL    SAFETY    RATCHET. 

The  ordinary  ratchet-wheel  is  a  disc  with  teeth  or  indenta- 
tions on  its  periphery,  and  in  practice  it  is  employed  in  combination 
with  a  pawl  or  dog  arranged  to  engage  with  its  teeth  in  such 
manner  that  the  ratchet-wheel,  being  attached  to  a  rotating  shaft, 
is  entirely  free  to  revolve  in  one  direction,  but,  by  the  action  of 
the  pawl,  is  prevented  from  rotation  in  the  contrary  direction. 
Thus  arranged  it  is  usually  attached  to  the  primary  shaft  of  a 
winch,  or  other  hoisting  gear,  so  that,  while  it  opposes  no 
resistance  to  rotation  of  the  shaft  in  the  direction  necessary  for 
hoisting,  it  effectively  prevents  motion  in  the  contrary  direction. 
When  it  is  desired  to  lower  the  load  the  pawl  is  thrown  out  of 
engagement  with  the  ratchet-wheel,  and  the  load  then  lowered  by 
turning  the  cranks  backward,  or  by  letting  go  of  the  cranks  and 
controlling  the  descent  of  the  load  by  a  brake  applied  to  the  shaft. 

Both  of  these  arrangements  are  dangerous,  and  are  productive 
of  serious  accidents.  Where  lowering  is  effected  by  turning  the 
cranks  backward  with  the  pressure  due  to  the  load  upon  them,  it 
frequently  happens  that  a  heavy  load  overcomes  the  operator,  in 
which  case  the  cranks  begin  to  revolve  with  great  violence  and 
often  strike  the  operator  before  he  can  escape  from  their  reach. 
Where  a  brake  is  used  there  is  less  danger,  but  even  then  the  safe 
descent  of  the  load  is  contingent  upon  the  skill  with  which  the 
brake  is  used,  and  any  lack  of  skill  or  watchfulness  will  result  in 
a  rapid  descent  of  the  load.  In  this  case,  if  the  motion  is  not 
checked  the  load  may  descend  so  rapidly  as  to  cause  damage, 
while  if  its  motion  be  suddenly  arrested  by  the  brake,  the  shock 
and  strain  thereby  induced  are  apt  to  damage  the  crane. 

A  Friction  Ratchet  is  one  in  which  the  action  of  friction  is 
substituted  for  the  teeth  and  pawl  of  the  common  ratchet,  so  that 
the  retaining  action  of  the  ratchet  will  take  place  instantly  and  in 
all  positions.  A  Safety  Ratchet  may  be  denned  as  one  in  which 
lowering  of  the  load  is  effected  by  reversing  the  motion  of  the 


34 


A   Treatise  on   Cranes. 


shaft  to  which  the  ratchet  is  attached  without  any  disengagement 
of  the  pawl  or  its  substitute,  the  construction  being  such  that  so 
long  as  this  backward  motion  is  continued  the  load  will  descend, 
but  that  when  it  is  discontinued  the  load  will  automatically  come 
to  rest,  from  which  it  follows  that  with  a  Safety  Ratchet  the 
cranks  or  handles  of  a  hoisting  machine  may  be  "  let  go  "  at  any 
time,  either  in  hoisting  or  in  lowering,  the  ratchet  thereupon 
automatically  holding  the  load  suspended  and  preventing  "running 
down  "  or  descent  of  the  load. 

The  great  desirability  of  so  important  a  result  has  long  been 
conceded,  but  most  of  the  devices  heretofore  invented  for  its 
accomplishment  have  been  so  complicated,  or  so  uncertain  in 
action,  as  to  find  little  favor.  These  objections,  however,  have 
been  fully  overcome  in  the  devices  employed  in  the  Weston  Cranes 
and  other  hoists,  some  of  which  are  described  below. 

No  one  form  of  Safety  Ratchet  is  applicable,  without 
modification,  to  all  of  the  varying  requirements  of  hoists  and 
cranes.  One  of  the  simplest  forms  is  that  employed  in  the 
Weston  Double-Lift  hoist,  (see  Part  IV)  the  general  construction 
of  which  is  as  follows  : 


FIG.  4.— "Double-Lift"  Safety  Ratchet. 

Fig.  4.  is  a  sectional  view  of  this  machine  in  which  A  is  the 
main  shaft  or  axle,  and  B  a  rope  wheel,  attached  to  one  end  of 
the  shaft,  by  means  of  which  motion  is  communicated  to  the  lat- 
ter through  an  endless  rope  or  chain  passing  over  the  wheel  and 
extending  downward  to  the  operating  floor.  C  is  a  pocketed 
chain  wheel  over  which  passes  the  hoisting  chain,  each  end  of 
which  latter  is  provided  with  a  hook  for  attaching  the  load.  The 


Crane  Details. — Frictional  Safety  Ratchet.     35 

center  of  this  wheel  is  tapped  with  a  screw-thread  coinciding 
with  a  screw  cut  upon  the  central  portion  of  the  shaft  A.  G  and 
H  are  two  ratchet-wheels  with  their  teeth  inclined  in  opposite 
directions.  Each  of  these  is  provided  with  a  suitable  pawl 
pivoted  to  the  frame  of  the  machine,  the  effect  of  which  is  to  permit 
each  wheel  to  revolve  in  one  direction,  but  to  prevent  its  rotation 
in  the  opposite  direction.  One  of  them  is  thus  free  to  revolve  to 
the  right  and  the  other  to  the  left.  E  and  F  are  collars  fitting  to 
the  shaft  and  pinned  fast  to  it  so  that  they  rotate  with  it.  Beyond 
these  collars  on  each  side  are  journals  in  which  the  shaft  A 
revolves  and  which  are  formed  within  the  frame  of  the  machine. 
The  action  of  this  machine  is  as  follows:  Supposing  the  load  to 
be  hung  on  that  side  of  the  chain  which  is  nearest  the  eye  in 
Fig.  4,  its  effect  is  to  cause  the  chain  wheel  C  to  rotate  forward, 
thus  screwing  it  upon  the  shaft  A  in  the  direction  of  the  ratchet- 
wheel  H.  As  soon  as  it  is  moved  into  contact  with  the  latter  the 
frictional  adherence  between  the  two  tends  to  rotate  the  ratchet- 
wheel  H  with  the  chain  wheel  C.  This  is  prevented,  however,  by 
the  pawl  engaging  with  the  wheel  H,  so  that  further  descent  of 
the  load  is  arrested.  Under  these  conditions  the  pull  of  the  load 
tends  to  screw  the  chain  wheel  C  further  to  the  right,  and  this  being 
prevented  by  its  pressure  against  the  ratchet-wheel  H,  which  in 
turn  is  supported  by  the  collar  F  pinned  to  the  shaft,  the  further 
tendency  of  the  load  is  to  rotate  all  of  the  parts  just  referred  to, 
this  action  being  prevented  by  the  pawl  engaging  with  the  ratchet- 
wheel  H.  If  now  the  hand  rope  passing  over  the  rope  wheel  B 
be  pulled  in  the  direction  necessary  to  cause  hoisting  of  the  load, 
all  of  the  parts  above  enumerated  will  remain  locked  into  engage- 
ment by  the  pull  of  the  load  and  will  rotate  together,  the  load 
thus  rising  in  the  usual  manner.  If  at  any  time  the  strain  on  the 
hand-rope  be  relaxed  the  pull  of  the  load  will  rotate  the  parts 
backward  until  the  pawl  engages  with  the  next  tooth  upon  the 
ratchet-wheel  H,  when  all  will  come  to  rest  and  remain  suspended 
as  before. 

If,  however,  the  rope-wheel  B  be  rotated  in  the  opposite 
direction,  in  order  to  lower  the  load,  the  following  action  will  occur. 
The  first  movement  of  the  wheel  B  will  cause  the  shaft  A  to 


36  A    Treatise  on  Cranes. 

rotate  in  a  direction  which  tends  to  unscrew  the  chain-wheel  C 
from  its  engagement  with  the  ratchet  H,  by  causing  it  to  move 
towards  the  left.  As  soon  as  this  unscrewing  has  progressed  to 
a  point  which  releases  the  frictional  engagement  of  the  wheel  C 
with  the  ratchet  H,  the  former  will  commence  to  revolve  under 
the  influence  of  the  load,  but  in  so  doing  will  overtake  the  shaft 
A  and  again  screw  itself  up  into  frictional  engagement  with  the 
ratchet  H.  The  continued  rotation  of  the  latter,  however,  will 
again  release  the  chain  wheel  C,  which  will  again  move  instantly 
forward  and  overtake  the  shaft.  In  point  of  fact,  these  succes- 
sive releasings  and  engagements  are  imaginary  rather  than 
actual,  the  real  action  consisting  of  forward  motion  of  the  screw 
upon  the  shaft  followed  by  a  corresponding  movement  of  the 
chain  wheel  under  the  influence  of  the  load,  the  forward  motion 
of  the  latter  continuing  so  long  as  the  shaft  is  rotated  by  the 
shaft  B,  but  ceasing  whenever  the  motion  of  the  latter  is  discon- 
tinued. The  action  of  lowering  which  thus  takes  place  is  per- 
fectly smooth  and  continuous,  and  is  effected  with  but  slight 
effort  upon  the  rope  wheel  B.  Upon  its  discontinuance  at  any 
time  the  pull  of  the  load  instantly  locks  the  chain  wheel  C  against 
the  ratchet  H,  which  in  turn  is  held  by  its  pawl,  and  the  parts 
immediately  come  to  rest  and  the  load  remains  suspended. 

Should  the  load  be  hung  upon  the  other  or  opposite  hook 
its  effect  will  be  to  screw  the  rope  wheel  C  against  the  ratchet- 
wheel  G,  the  teeth  of  which  are  inclined  in  a  direction  opposite 
to  those  of  the  wheel  H.  In  this  case  the  same  action  as  above 
described  takes  place,  but  in  a  contrary  direction,  the  ratchet- 
wheel  G  holding  the  load  suspended  and  the  wheel  H  moving 
idly  with  the  shaft. 

Although  somewhat  compli- 
cated to  describe,  the  action  of 
this  machine  is  exceedingly  sim- 
ple and  is  absolutely  reliable 
under  all  conditions,  as  is  well 
known  to  the  many  users  of  the 
Weston  Double  Lifts,  in  which  it 

FIG.  5. — Spur  Pinion  with  Safety  Ratchet,    jg  employed. 


Crane  Details. — Frictional  Safety  Ratchet.      37 

Another  form  of  safety  frictional  ratchet  is  shown  in  Fig.  5, 
in  which  A  is  the  primary  shaft  of  a  hoist  and  D  a  spur  pinion 
carried  by  said  shaft  and  gearing  into  a  proper  spur  wheel  upon 
the  second  shaft.  C  is  a  ratchet-wheel  having  teeth  on  its 
periphery  which  engage  with  an  ordinary  pawl  pivoted  to 
the  frame  of  the  machine,  thereby  preventing  its  rotation  except 
in  one  direction.  E  is  a  collar  screwed  and  pinned  fast  to 
the  shaft  A  so  that  it  rotates  with  it,  and  B  a  similar  collar  at 
the  opposite  side.  The  collar  A  has  a  helix  formed  upon  its 
side  which  adjoins  the  pinion  D,  and  the  hub  of  the  latter  has  a 
corresponding  helix,  so  that  the  two  when  in  coincidence  appear  as 
shown  in  the  cut.  The  pinion  D  and  ratchet  C  are  loose  upon 
the  shaft  A.  Assuming  that  to  effect  hoisting  the  shaft  A  must 
be  revolved  so  that  its  upper  surface,  as  seen  in  Fig.  5,  moves 
toward  the  eye,  in  which  case  the  resistance  due  to  the  load  tends 
to  retard  or  hold  back  the  pinion  D,  the  shoulder  upon  the  collar 
E,  as  the  latter  revolves  with  the  shaft  A,  will  move  away  from 
the  corresponding  shoulder  upon  the  hub  of  the  pinion  D,  the 
effect  of  which  is  to  cause  the  two  helices  to  mount  upon  each 
other,  thereby  pushing  the  pinion  D  to  the  right  upon  the  shaft 
and  forcing  it  into  frictional  engagement  with  the  ratchet-wheel 
C.  The  latter  being  supported  by  the  fixed  collar  B,  the  several 
parts  are  thus  locked  together  and  will  thereupon  rotate  simul- 
taneously, the  teeth  of  the  ratchet  C  being  inclined  so  as  to  per- 
mit of  motion  in  this  direction.  If  at  any  time  the  rotation  of 
the  shaft  A  be  discontinued  the  pressure  due  to  the  load  will  tend 
to  rotate  the  pinion  B  backwards,  but  all  of  the  parts  being  locked 
together,  as  already  explained,  backward  motion  is  prevented  by  the 
action  of  the  ratchet-wheel  C  and  the  load  will  thus  remain  sus- 
pended. 

When  it  is  desired  to  effect  lowering,  the  shaft  A  must  be 
positively  rotated  backwards,  the  effect  of  which  will  be  to  relax 
the  longitudinal  engagement  of  the  several  parts  by  the  rotation 
of  the  collar  E,  the  helix  upon  which  will  thus  move  forward  into 
coincidence  with  the  corresponding  helix  on  the  hub  of  the  pinion 
B.  As  soon  as  this  movement  of  the  collar  E  is  sufficient  to  relax 
the  longitudinal  pressure,  the  pull  of  the  load  will  cause  the 


38  A  Treatise  on  Cranes. 

pinion  B  to  follow  the  rotation  of  the  shaft  and  to  overtake  the 
collar  E,  thereby  again  applying  the  longitudinal  pressure  unless 
the  continued  backward  motion  of  the  shaft  again  releases  it. 
This  alternate  releasing  and  re-engagement  will  then  continue  so 
long  as  the  shaft  is  revolved  backward,  in  a  manner  precisely 
similar  to  that  occurring  in  the  Double-Lift  mechanism  shown  by 
Fig.  4.  During  this  reverse  motion  of  lowering,  the  ratchet-wheel 
C  remains  stationary  by  reason  of  the  engagement  of  the  pawl 
with  its  teeth.  Should  the  pinion  D  from  any  cause  fail  to  follow 
the  shaft  in  its  backward  motion  the  shoulder  upon  the  collar  E 
will  immediately  overtake  the  corresponding  shoulder  on  the  hub 
of  the  pinion,  and  the  latter  will  thereupon  be  positively  driven 
backward.  If  desirable  to  increase  the  frictional  adherence 
between  the  pinion  D  and  the  ratchet  C,  a  series  of  Weston  friction 
discs  may  be  interposed  between  their  abutting  surfaces,  as  shown 
in  Fig.  5. 


FIG.  6. — Safety  Spur  Pinion. 

In  each  of  the  preceding  examples  an  ordinary  ratchet-wheel 
and  pawl  is  employed  to  prevent  backward  motion  of  the  shaft 
under  the  influence  of  the  load.  Fig.  6  represents  another  form 
in  which  the  ratchet  also  is  frictional  and  no  toothed  ratchet- 
wheel  is  required.  In  this  case  the  pinion  A  and  the  frictional 
ratchet  or  collar  B  are  both  loose  upon  their  shaft  C.  The 
adjacent  hubs  of  these  two  parts  have  formed  upon  them  a  helix 


Crane  Details. — Frictional  Safety  Ratchet.     39— 

similar  to  that  shown  in  Fig.  5,  so  that  when  turned  in  contrary 
directions  the  two  helical  surfaces  mount  upon  each  other  and 
produce  a  longitudinal  pressure  which  locks  the  several  parts  into 
frictional  engagement  with  the  sides  of  the  housing  E,  and  so 
prevents  the  backward  rotation  of  the  pinion  under  the  pressure 
of  the  load.  In  this  case  the  parts  occupy  the  relative  positions 
shown  in  the  sectional  view,  the  cross-pin  which  is  attached  to  the 
shaft  standing  midway  between  the  two  shoulders  on  the  opposite 
helices.  If  the  shaft  be  rotated  in  a  direction  to  cause  hoisting, 
the  cross-key  D  moves  forward  until  it  picks  up  both  the  pinion 
A  and  collar  B  by  pressing  against  the  slotted  openings  in  their 
hubs,  and  thus  presses  them  into  a  position  where  the  longitudinal 
pressure  of  the  helices  is  relaxed  and  the  parts  rotate  freely  with 
the  shaft.  If  this  action  be  discontinued  while  the  load  is 
suspended  the  pinion  A  will  rotate  backward  through  a  small  arc 
carrying  with  it  the  key  D  and  shaft  C,  while  the  collar  B  remains 
stationary,  and  in  this  way  the  helical  hubs  restore  the  end  pressure 
and  the  parts  are  again  locked  fast.  If  the  shaft  then  be  rotated 
backward,  the  key  D  will  first  pick  up  the  collar  B  by  pressing 
against  the  slot  in  its  hub  and  move  it  forward  into  coincidence 
with  the  corresponding  slot  in  the  hub  of  the  wheel  A,  when,  the 
end  pressure  being  relaxed,  the  parts  will  again  rotate  freely  so 
long  as  the  shaft  is  turned  backward,  but  upon  the  discontinuance 
of  this  motion  the  pressure  of  the  load  will  again  move  the  wheel 
A  backward  until  the  end  pressure  is  restored.  The  exterior 
frictional  face  of  the  collar  B  is  of  larger  diameter  than  that  which 
abuts  against  the  hub  of  the  pinion  A,  and  the  frictional  resistance 
against  the  frame,  thus  acting  at  a  greater  radius,  is  sufficient  to 
resist  the  strain  of  the  load  and  hold  the  pinion  stationary. 

Fig.  7  represents  the  same  arrangement  as  that  just  previously 
described  in  its  application  to  a  worm.  The  force  necessary  to 
prevent  backward  motion  of  a  worm  under  the  pressure  due  to  the 
load  is  usually  quite  small,  and  this  device  thus  becomes 
particulary  applicable,  owing  to  its  simplicity  and  compactness. 

From  the  foregoing  the  general  character  of   the  frictional 

safety  ratchets  employed  in  the  Weston  Cranes  will  be  understood. 

Although   difficult   to   describe   in   this  manner  they   are   all 


40  A   Treatise  on  Cranes. 

exceedingly  simple,  both  in  construction  and  action,  and  have  now 
been  so  thoroughly  tested  under  the  most  varying  conditions  of 
service  as  to  make  their  employment  no  longer  experimental  or  of 
doubtful  expediency.  Their  application  to  the  varying  require- 


FIG.  7. — Safety  Worm-Pinion. 


ments  of  crane  construction  requires  numerous  modifications 
which  are  not  here  shown,  but  the  essential  principles  of  all  are 
substantially  identical  with  those  above  described. 


Crane  Details. — Clutches. 


41- 


CLUTCHES. 

In  all  cranes  operated  by  power  one  or  more  clutches  are 
essential  to  the  convenient  operation  of  the  mechanism.  Expe- 
rience has  demonstrated  that  the  best  and  most  reliable  clutch  for 
this  purpose  is  that  invented  and  patented  by  Mr.  Thomas  A. 
Weston,  M.  E.,  and  first  fully  described  in  a  paper  read  by  him 
before  the  British  Institution  of  Mechanical  Engineers,  from 
which  we  condense  the  following  description,  and  extract  the 
cuts  by  which  it  is  illustrated. 

The  essential  basis  of  the  Weston  Clutch  or  coupling  consists 
of  two  series  of  friction  discs  arranged  alternately  with  each 
other  upon  a  common  axis,  one  series  being  carried  by  one  shaft, 
and  the  other  series  connected  to  the  other  shaft  or  wheel  which 
is  required  to  be  coupled  with  the  first  shaft.  The  great  advan- 
tage arising  from  this  alternate  arrangement  of  the  discs  is  that 
the  frictional  effect  of  any  pressure  applied  to  couple  them  is 
repeated  as  many  times  as  there  are  discs  in  the  two  series,  that 
is,  the  number  of  all  the  discs  is  a  constant  multiplier  for  the 
friction  produced  between  a  single  pair  of  the  rubbing  surfaces 
by  any  given  pressure. 


FIG.  8. — Model  of  Alternate  Friction  Plates. 


This  principle  of  the  multiplication  of  frictional  surfaces 
is  illustrated  by  the  diagram,  Fig.  8,  where,  instead  of  two  series 
of  discs,  there  are  shown  two  series  of  short,  flat  plates,  arranged 


42  A  Treatise  on  Cranes. 

like  the  discs,  alternately  with  each  other.  The  one  series  AA 
are  severally  tied  to  the  fixed  pillar  C,  and  each  one  of  the  other 
series  BB  has  its  sides  in  frictional  contact  with  two  of  the  first 
series.  The  applied  pressure  for  frictionally  coupling  the  two 
series  is  furnished  by  the  weight  D.  Upon  withdrawing  any  one 
of  the  series  B  in  the  direction  shown  by  the  arrow,  a  certain 
degree  of  resistance  will  occur,  in  consequence  of  the  friction 
upon  its  two  sides  due  to  the  pressure  of  the  weight  D.  Upon 
withdrawing  two  of  the  series  B  together,  twice  as  much  resist- 
ance occurs  ;  and  if  the  whole  series  BB  are  simultaneously  with- 
drawn, the  resistance  is  further  increased  in  proportion  to  the 
whole  number  in  that  series.  Hence,  as  the  number  of  the  plates 
or  discs  may  be  indefinitely  increased,  an  indefinite  increase  or 
extension  of  frictional  area  may  be  obtained  without  any  reduc- 
tion of  the  pressure  per  square  inch  upon  the  rubbing  surfaces  ; 
in  consequence  of  which  the  remarkable  result  is  obtained  of  an 
indefinite  increase  in  the  total  amount  of  friction  with  the  same 
load. 

In  Fig.  9,  is  represented  a  form  of  experimental  friction 
brake,  or  coupling,  composed  of  two  series  of  circular  friction 
discs  AA  and  BB,  the  relative  motion  of  the  rubbing  surfaces 
being  circular  instead  of  in  a  straight  line,  as  in  Fig.  8.  The 
shaft  discs  A  are  made  an  easy  fit  upon  the  square  shaft  C,  so 
that  they  may  slide  to  or  from  each  other  upon  the  shaft  into 
more  or  less  intimate  contact  with  the  intermediate  discs  B  ;  and 
the  latter,  when  no  coupling  pressure  is  applied,  are  capable  of 
turning  freely  upon  the  circular  bosses  of  the  shaft  discs  A.  The 
coupling  pressure  is  applied  or  withdrawn  by  means  of  the  crank- 
lever  D,  the  short  forked  arm  of  the  lever  compressing  the  discs 
longitudinally  upon  the  shaft  against  the  fixed  pin  E.  So  long 
as  no  compression  is  applied,  the  shaft  C  can  rotate  freely,  carry- 
ing with  it  the  discs  A,  which  do  not  then  transmit  any  driving 
force  to  the  discs  B  ;  but  upon  compressing  the  discs  into  fric- 
tional contact  with  each  other,  the  rotary  motion  of  the  shaft  will 
be  transmitted  by  the  discs  A  to  the  intermediate  discs  B.  The 
rotation  of  the  shaft  being  maintained,  and  the  discs  B  being  held 
from  turning  by  a  cord  F  wound  round  the  circumference  of  each, 


Crane  Details. — Clu tches. 


43 


the  tension  upon  each  cord  measures  the  friction  between  each 
two  pairs  of  the  circular  rubbing  surfaces  ;  and  the  strain  upon 


FIG,  9. — Experimental  Friction  Brake. 

all  the  cords  taken  together  is  the  total  force  which  the  whole 
series   of    intermediate   discs   B   is   then    absorbing    by    brake 


44 


A  Treatise  on  Cranes. 


action  upon  the  shaft  discs  A.  This  strain  is  indicated  by  the 
spring  balance  H,  upon  which  all  the  cords  pull  by  the  interven- 
tion of  the  cross-bar  G.  To  illustrate  the  uniformity  of  action  of 
the  device,  the  coupling  pressure  at  D  may  be  applied  gently 
and  increased  by  imperceptible  gradations  to  any  required  extent, 
and  in  like  manner  be  gradually  withdrawn  again  ;  and  the  tan- 
gential force  indicated  by  the  spring  balance  H  will  simultaneous- 
ly rise  and  fall  with  the  same  steady  regularity.  The  coupling 
pressure  may  also  be  applied  and  withdrawn  very  suddenly,  or 
even  with  a  jerk,  and  proportionate  extremes  of  force  will  then 
be  indicated  with  the  same  abruptness  by  the  spring  balance  H. 
This  sensitiveness  of  the  friction  coupling  is  due  to  the  parallelism 


FIG.  io.— Frictional  Shaft  Coupling. 

of  its  rubbing  surfaces,  since  the  frictional  action  between  parallel 
plain  surfaces  necessarily  fluctuates  in  true  and  instant  correspon- 
dence with  every  variation  of  the  applied  pressure. 


Crane  Details. — Clutches. 


45- 


In  Fig.  10  is  shown,  in  longitudinal  section,  a  simple  form  of 
shaft  coupling;  and  in  Figs,  n  and  12,  transverse  sections  show- 
ing the  alternate  iron  and  wood  discs  separately.  The  five  iron 
discs  A  engage  with  solid  keys  on  the  long  boss  of  the  spur 
wheel  E,  within  which  the  driving  shaft  C  turns  freely  when  no 
coupling  pressure  is  applied  to  the  discs.  The  drum  D  contain- 
ing the  six  intermediate  wood  discs  B,  slides  on  feathers  on  the 


FIG.  ii. 


FIG.  12. 


shaft  C,  and  the  groove  G  on  the  outer  end  of  the  drum  receives 
the  forked  end  of  a  lever  by  which  the  coupling  pressure  is 
applied,  compressing  the  discs  against  the  fixed  collar  F  on  the 
shaft,  and  thereby  coupling  the  spur  wheel  E  to  the  shaft  C.  .  . 

The   paper   from  which  these  extracts  are  quoted 

contains  a  number  of  other  illustrations  and  descriptions  indicat- 
ing the  wide  range  of  applicability  of  the  Weston  Frictional 
Coupling,  and  demonstrating  its  convenience  and  efficiency  under 
the  most  varied  conditions. 

The  Weston  Clutch,  then,  consists  essentially  of  two  series 
of  thin  discs,  one  series  locked,  by  the  central  openings,  to  its 


46  A  Treatise  on  Cranes. 

shaft,  and  the  other  series  locked,  by  their  peripheries,  through 
the  medium  of  a  surrounding  box  or  shell,  to  the  other  shaft, 
both  series  being  free  to  slide  longitudinally  upon  their  shafts, 
and  thus  being  capable  of  engagement  by  longitudinal  pressure. 
The  system  admits  of  indefinite  expansion  as  to  its  power,  either 
by  multiplying  the  number  of  discs  in  each  series,  which  slightly 
increases  the  longitudinal  space  occupied  ;  or  by  enlarging  the 
diameter  of  the  discs,  and  thus  increasing  the  radius  at  which 
their  frictional  resistance  acts,  the  result  of  which  is  to  enlarge 
the  diametral  dimensions  of  the  clutch. 

The  Weston  Disc  Clutch  has  already  been  tested  by  years  of 
constant  use  under  varied  conditions  and  heavy  duty.  It  has 
been  found  applicable  not  only  to  the  transmission  of  small 
amounts  of  power  through  light  shafting,  but  equally  to  the 
transmission  of  large  amounts  of  power,  and  to  the  resistance  of 
the  severest  strains,  as,  for  example,  in  operating  the  mechanism 
of  powerful  dredging  machines,  and  in  driving  the  heaviest 
rolling  mill  machinery.  For  this  latter  purpose  Weston  Disc 
Clutches  have  been  built  with  capacity  to  transmit  the  entire 
power  of  a  1000  horse-power  steam  engine  used  in  driving  a  train 
of  rolls  for  making  rails,  the  purpose  of  the  clutch  being  to 
reverse  the  motion  of  the  train.  In  this  case  the  discs  were  9 
feet  in  diameter  and  i  inch  thick,  of  wrought  iron.  These  latter 
clutches  have  been  some  time  in  use  and  have  operated  in  a 
perfect  manner. 

The  Weston  Clutch  exceeds  all  others  in  compactness,  as  well 
as  in  its  capacity  for  indefinite  expansion,  and  has  the  additional 
merit  of  great  simplicity  and  great  durability.  Experience  has 
proven  that  for  most  purposes  it  is  best  to  use  iron  or  steel  discs 
exclusively  ;  and  that  these,  properly  made,  will  last  for  years 
without  any  apparent  wear. 


Crane  Details. —  The  West  on- Capen  Clutch.     47— 


THE    WESTON-CAPEN    CLUTCH. 

To  adapt  the  Weston  Disc  Clutch  to  crane  work  it  became 
essential  to  provide  a  means  of  conveniently  applying  the  longi- 
tudinal pressure  upon  the  discs  without  thereby  inducing  any 
collar  friction.  This  is  effected  by  the  patented  improvements 
of  Mr.  T.  W.  Capen  described  below,  the  objects  of  which  are  to 
produce  end-pressure  between  two  pieces,  both  attached  to  and 
revolving  with  an  ordinary  shaft,  and  to  do  this,  whether  the  shaft 
be  in  motion  or  at  rest,  without  causing  any  additional  friction, 
either  upon  the  journals  or  the  collars. 


FIG.  13. — Friction  Pullies  with  Capen  Toggles. 


Fig.  13,  above,  represents  the  Capen  toggle  device  as  applied 
to  an  ordinary  friction  clutch,  in  which  the  friction  is  obtained 
from  a  pair  of  inclined  surfaces,  at  the  periphery  of  the  wheels, 
held  in  engagement  by  longitudinal  pressure.  The  toggles  are 
used  to  effect  this  pressure,  and  their  action  will  be  readily  seen 
by  reference  to  the  cut.  The  lever  H  is  contained  within  the 
slot  m  of  the  shaft,  and  is  pivoted  to  the  latter  by  a  pin/.  One 
arm  of  this  lever  is  connected  by  a  link  I  to  a  pin  w  which  passes 
through  the  shaft  and  through  the  hub  y  of  the  clutch  D.  The 
other  arm  of  the  lever  is  similarly  connected  by  a  link  V  and  a 
pin  w'  to  the  clutch  D'.  The  holes  in  the  shaft  through  which 
the  pins  w  and  w'  pass,  are  elongated  so  that  each  clutch  may 


48  A  Treatise  on  Cranes. 

have  a  limited  sliding  movement  on  the  shaft,  without  being  able 
to  turn  independently  on  the  same. 

Sliding  upon  the  shaft  between  the  clutches  is  the  sleeve  or 
collar  G,  which  is  provided  with  a  projection  //  (shaded  black  in 
the  cut),  fitted  into  and  moving  freely  within  the  slot  m  of  the 
shaft.  The  central  portion  of  this  projection  h  is  straight  and 
parallel  with  the  shaft,  while  at  each  end  is  an  incline  or  bevel. 

As  shown  in  Fig.  13,  the  sleeve  G  has  been  moved  in  the 
direction  of  the  arrow  so  far  that  one  arm  of  the  lever  H  has 
been  depressed  so  that  its  center  line  coincides  with  the  center 
line  of  the  link  I',  and  the  clutch  D'  thus  moved  into  rigid  en- 
gagement with  the  frictional  surface  of  the  pulley  A' ;  at  the 
same  time,  the  tilting  of  the  other  end  of  the  lever  H,  acting 
through  the  link  I,  has  caused  the  disc  D  to  be  removed  from 
frictional  contact  with  its  pulley  A.  In  this  position  the  straight 
portion  of  the  projection  h  bears  on  the  link  I',  and  holds  it  in 
position,  without  requiring  any  effort  or  strain  to  keep  the  sleeve 
G  in  position.  The  latter  may  be  moved  by  the  ordinary  forked 
shipping  lever,  but  it  will  be  seen  that  the  action  of  the  collar  G 
holds  the  clutches  in  their  relative  positions  independently  of  any 
aid  from  the  mechanism  for  operating  the  sleeve,  and  thus  avoids 
all  end-thrust  and  collar  friction  upon  the  shaft,  the  coupling 
pressure  being  self-contained  between  the  shaft  and  the  rotating 
parts.  Upon  moving  the  sleeve  G  in  a  direction  contrary  to  the 
arrow,  the  link  I  is  depressed  and  the  clutch  D  forced  into 
engagement  with  its  pulley  A,  while  at  the  same  time  the  link  I 
is  drawn  up  and  back,  thus  positively  disengaging  the  clutch  D' 
from  its  pulley.  If  the  sleeve  be  adjusted  to  a  position  midway 
between  the  clutches,  both  of  the  latter  will  be  free  from  contact 
with  their  respective  pullies.  The  foregoing  illustrates  the  sim- 
plest form  of  the  toggle  device.  Its  application  to  the  Weston 
Disc  Clutch  is  illustrated  in  Fig.  14. 

Fig.  14  is  a  cross-section  and  end  elevation  of  a  Weston  Disc 
Clutch  with  the  end-thrust  upon  the  discs  effected  by  a  simple 
forked  lever  of  the  ordinary  type.  The  principal  parts  consist  of 
the  wheel  or  pulley  A  running  loose  upon  the  shaft  B,  to  which 
it  is  to  be  connected  by  means  of  the  clutch  when  desired,  and 


Crane  Details. —  The  Weston-Capen  Clutch.      49 _ 


the  follower  C,  the  hub  of  which  is  bored  to  fit  freely  upon  the 
shaft  B  so  as  to  move  longitudinally  thereon.  This  hub  is  key- 
seated  to  fit  the  key  or  spline  c  upon  the  shaft  B,  so  that  while 
the  follower  is  free  to  slide  longitudinally  upon  the  shaft,  neither 
can  revolve  without  carrying  with  it  the  other.  Within  the  wheel 
A  are  the  two  series  of  discs  XX  and  YY.  These  are  most 
clearly  seen  in  the  end  elevation,  in  the  upper  half  of  which  is 
shown  a  portion  of  one  of  the  discs  X,  the  central  opening  of 
which  fits  closely  upon  the  square  hub  c'  of  the  follower  C,  while 
in  the  lower  half  is  shown  a  portion  of  one  of  the  discs  Y,  the 
central  aperture  of  which  is  circular,  and  large  enough  to  avoid 


FIG.  14. — Simple  Form  of  Weston  Clutch. 

contact  with  the  square  hub  c1 ',  while  its  periphery,  being  larger 
than  that  of  the  disc  X,  extends  to  the  interior  periphery  of  the 
rim  of  the  wheel  A,  and  is  engaged  with  the  latter  by  means  of 
notches  fitting  over  the  several  ribs  da! .  It  follows,  of  course, 
that  the  discs  XX  must  all  rotate  with  the  follower  C,  by  reason 
of  their  engagement  with  its  square  hub  c' ',  and  that  the  discs  YY 
must  all  rotate  with  the  wheel  A  by  reason  of  their  engagement 
with  it  through  the  ribs  a' a'.  Each  series  of  discs,  however,  is 
free  to  slide  longitudinally,  the  one  upon  the  hub  c'  and  the  other 
upon  the  ribs  a' a',  so  that,  while  the  shaft  B,  being  suitably  driven. 


50  A    Treatise  on  Cranes. 

may  revolve  at  any  desired  speed,  the  wheel  or  pulley  A  need 
not  revolve  with  it,  but  may  remain  at  rest.  Now,  by  pulling 
the  hand  lever  so  as  to  cause  longitudinal  pressure  between  the 
two  series  of  discs,  the  follower  C,  which  rotates  with  the  shaft  B, 
will  be  frictionally  engaged  with  the  wheel  A,  thus  clutching  the 
two  together  and  causing  the  wheel  to  rotate  with  the  shaft. 

The  fulcrum  of  the  hand  lever  being  upon  some  fixed 
support,  the  construction  shown  in  Fig.  14  would  necessarily  in- 
volve considerable  friction  between  the  forked  hand  lever  and 
the  hub  or  collar  of  the  follower  C,  the  amount  of  this  friction 
depending  upon  the  longitudinal  pressure  required  to  develop 
sufficient  adhesion  between  the  disc  surfaces  to  transmit  the 
desired  amount  of  power.  The  collar  friction  thus  generated 
would  consume  a  considerable  proportion  of  the  power  transmit- 
ted, and  would  involve  serious  wear  upon  the  parts.  All  trouble 
of  this  kind  is  obviated  by  the  application  of  the  Capen  toggle 
device,  in  the  manner  illustrated  below. 


FIG.  15.— Weston  Clutch  with  Capen  Toggles. 

Fig.  15  is  a  cross-section  and  end  elevation  of  a  Weston 
Disc  Clutch  with  the  Capen  toggle  device  applied  for  producing 
the  necessary  end-thrust  upon  the  discs.  The  several  parts  of 
the  clutch  are  substantially  the  same  as  in  Fig.  14,  except  that  to 
the  right  of  the  follower  C  is  the  separate  hub  K  secured  to  the 
shaft  B  by  two  pins  k'k '.  The  hub  K  is  grooved  upon  two  of  its 
opposite  sides,  and  within  these  grooves  are  located  the  toggles 
FF.  Sliding  upon  the  hub  K  is  the  grooved  ring  or  collar  E,  the 


Crane  Details. —  The  Weston-Capen  Clutch.      51 


internal  surface  of  which  acts  upon  the  toggles  FF,  while  its 
external  surface  is  grooved  to  permit  of  engagement  with  an 
ordinary  forked  lever,  substantially  as  shown  in  Fig.  14.  The 
construction  and  action  of  the  toggles  is  shown  to  an  enlarged 
scale  in  Figs.  16  and  17,  in  which  L  indicates  the  pin  by  which 
the  toggle  F  is  pivoted  to  the  hub  K,  and  N  is  the  link  which 
unites  the  toggle  F  to  the  follower  C  (Fig.  15).  M  is  a  roller, 
turning  upon  the  pin  which  unites  the  link  N  to  the  toggle  F,  the 
purpose  of  this  roller  being  to  relieve  the  friction  of  the  collar  E 
when  acting  to  press  the  toggle  into  the  position  shown  in  Fig.  16 
to  cause  longitudinal  pressure  upon  the  discs.  As  shown  in  Fig. 
17,  the  collar  E  is  withdrawn  to  the  position  it  occupies  when  the 
discs  are  relieved  from  pressure  and  the  clutch  is  disengaged 
To  effect  clutching  the  collar  E  is  moved  to  the  left  until  it 

occupies  the  position  shown  in 
Fig.  16,  in  doing  which  it  comes  in 
contact  with  the  roller  M  and  de- 
presses the  left  hand  end  of  the 
toggle  F,  thus  causing  it  to  assume 
the  position  indicated  in  Fig.  16. 
At  the  first  moment  of  contact 
between  the  collar  E  and  the 
roller  M  there  is  a  slight  amount 
of  resistance,  but  as  soon  as  the 
collar  E  has  passed  over  the  roller 
M  this  disappears  entirely,  all  of 
the  parts  shown  in  Figs.  16  and 
17  then  rotating  simultaneously 
with  the  shaft,  and  the  forked 
end  of  the  clutch  lever  lying 
loosely  within  the  groove  of  the 
collar  E.  The  longitudinal  pres- 
sure developed  by  the  toggle  when  in  the  position  shown  in 
Fig.  1 6  is  transmitted  directly  from  the  pin  L  (which  is  supported 
by  the  hub  K,  which  in  turn  is  pinned  to  the  shaft  B)  through  the 
link  N  to  the  follower  C  (see  Fig.  15),  whence  it  passes  through 
the  two  series  of  discs  to  the  wheel  A,  through  the  hub  of  which 


FIG.  17. 


52  A    Treatise  on  Cranes. 

it  is  transmitted  to  the  collar  b  on  the  shaft  B.  It  is  evident, 
therefore,  that  the  longitudinal  pressure  -employed  for  causing 
engagement  between  the  two  series  of  discs  is  borne  directly  by 
the  shaft  B,  the  collar  b  acting  as  one  abutment  and  the  pins  k'k' 
as  the  other,  the  longitudinal  pressure  being  expended  between 
them,  and  all  of  the  strained  parts  rotating  together. 

Both  series  of  discs  being  of  metal,  it  becomes  necessary  to 
make  a  close  adjustment  of  the  relative  longitudinal  positions  of 
the  wheel  A  and  the  follower  C,  so  that  when  the  clutch  is 
engaged  the  proper  pressure  may  be  exerted  upon  the  discs 
enclosed  between  them,  and  so  that  any  wear  of  the  parts  may 
be  conveniently  taken  up  and  the  adjustment  restored.  To 
accomplish  this  the  adjusting  device  shown  in  Figs.  18,  19  and 
20  is  employed. 


FIG.  i 


In  Fig.  1 8  is  represented  the  hub  K,  and  connecting  parts, 
precisely  as  shown  in  Fig.  15.  Figs.  19  and  20  show  the  follower 
C  with  the  adjusting  device  added.  The  follower  C  is  somewhat 
reduced  in  diameter  and  upon  its  periphery  a  fine  screw-thread 
is  cut.  Over  this  passes  the  adjusting  ring  M,  the  central 
opening  of  which  is  threaded  to  screw  upon  the  exterior  of  the 
follower  C.  Thus  arranged,  the  contact  of  the  follower  with 
the  discs  (see  Fig.  15)  is  through  the  medium  of  the  ring  M,  so 
that  by  screwing  the  latter  forward  or  back  upon  the  follower 
C  the  engagement  of  the  latter  with  the  discs  may  be  varied  to 
give  the  exact  amount  of  pressure  desired.  The  adjusting  ring 
M  is  provided  with  two  set-screws  H  and  I  (Fig.  20),  and  upon 
the  periphery  of  the  follower  C  are  eight  longitudinal  grooves  JJ 


Crane  Details. —  The  Weston-Capen  Clutch.      53 

of  beveled  section,  as  shown  in  Figs.  19  and  20.  The  screws  H 
and  I  are  separated  by  a  distance  slightly  less  than  the  pitch  of 
the  grooves  JJ,  so  that  when  the  beveled  point  of  the  screw  H 
bears  against  the  right  hand  side  of  one  groove,  the  beveled 
point  of  the  screw  I  will  bear  against  the  opposite  or  left  hand 
side  of  the  adjacent  groove.  In  this  way  a  pinch,  or  locking 
action,  is  obtained  which  holds  the  several  parts  in  rigid  engage- 
ment and  prevents  all  looseness  or  play.  By  backing  out  the 
screws  H  and  I  the  adjusting  ring  M  can  be  turned  upon  the 
screw-thread  to  the  proper  point  and  then  rigidly  secured  again 
to  the  follower  C  by  tightening  the  set-screws  H  and  I. 

The  foregoing  cuts  and  descriptions  illustrate  clearly  the 
construction  and  action  of  the  Weston-Capen  Clutch  as  applied 
to  the  engagement  of  a  spur  wheel  or  pulley  with  a  shaft,  whether 
for  the  transmission  of  power  from  the  shaft  to  the  wheel  or  from 
the  wheel  to  the  shaft.  By  a  slight  modification  of  the  external 
parts  the  clutch  is  equally  adapted  to  the  engagement  of  one 
shaft  with  another.  In  all  of  its  various  forms  the  Weston-Capen 
Clutch  posseses  entire  freedom  from  collar  friction,  and  the 
capability  of  adaptation  to  the  widest  range  of  uses.  It  is  equally 
sensitive  and  reliable  in  its  smallest  and  in  its  largest  forms, 
whether  in  the  counter-shaft  of  a  lathe  or  upon  the  main  driving 
shaft  of  a  large  engine.  Its  parts,  being  entirely  of  metal,  are 
unaffected  by  atmospheric  changes,  either  of  temperature  or 
moisture,  and  the  provision  for  adjustment  enables  the  pressure 
upon  the  discs  caused  by  the  action  of  the  toggles  to  be  regulated 
with  the  most  perfect  nicety,  according  to  the  varying  require- 
ments of  the  work  to  be  done.  The  parts  composing  the  clutch 
are  few  and  simple,  and  the  wear  is  chiefly  upon  the  metal  discs, 
which  are  easily  and  cheaply  renewed  when  necessary.  In 
economy  of  weight  of  revolving  parts  and  of  space  occupied,  and 
for  absolute  reliability  under  all  conditions  of  use,  experience  has 
proved  that  this  clutch  excels  all  others,  particularly  in  adapta- 
bility for  use  in  the  mechanism  of  cranes. 


54 


A    Treatise  on  Cranes. 


SQUARING    DEVICE    FOR    MOVABLE    CRANE    BRIDGES. 

For  the  reasons  stated  under  the  title  of  "  Traverse  Gear," 
in  Part  I,  it  is  found  that  "  a  perfect  system  of  bridge  propulsion 
must  hold  the  bridge  always  absolutely  square  with  its  tracks, 
and  must  propel  the  opposite  ends  of  the  bridge  in  the  same 
direction,  at  the  same  time,  and  at  the  same  speed."  The 
device  by  which  this  important  purpose  is  effected  in  the  Weston 
Traveling  Cranes  is  illustrated  and  described  below. 


FIG.  21. — Device  for  Squaring  Movable  Bridges. 

Fig.  21  represents  a  simple  form  of  overhead  crane  consist- 
ing of  a  pair  of  longitudinal  tracks  A  A,  resting  upon  which  is  the 


Crane  Details. — Squaring  Device.  55 

bridge  B,  provided  at  each  end  with  a  two-wheeled  truck  CC 
the  wheels  of  which  move  upon  the  track  and  support  the  bridge. 
Attached  to  the  bridge  are  four  guide  sheaves  D,  E,  F,  F,  the 
two  latter  being  upon  a  common  axis,  one  above  the  other.  At 
one  end  is  shown  the  wall  W  of  the  building  containing  the 
crane  and  supporting  the  ends  of  the  longitudinal  tracks.  Two 
wire  ropes,  indicated  respectively  by  the  letters  X  and  Y,  acting 
through  the  medium  of  the  guide  sheaves,  constitute  the  squaring 
device  for  the  bridge.  The  rope  X  is  made  fast  to  the  end-wall 
W  at  the  point  X',  and  leads  thence  around  the  upper  guide 
sheave  F,  across  the  bridge,  around  the  guide  sheave  E,  and  so 
to  the  opposite  end  of  the  longitudinal  tracks,  where  it  is  made 
fast  to  another  wall,  or  other  suitable  abutment,  in  the  same 
manner  as  at  the  starting  point  X'.  The  other  rope  Y  is  attached 
in  like  manner  to  the  wall  W  at  the  point  Y'  and  passes  first 
around  the  guide  sheave  D,  then  across  the  bridge  and  around 
the  lower  sheave  F,  and  so  to  the  opposite  end  of  the  tracks, 
where  it  is  made  fast  in  the  same  manner  as  at  the  starting  point 
Y'.  Each  of  these  two  ropes,  therefore,  starts  from  a  fixed  point 
or  abutment  at  one  end  of  the  tracks,  and  is  made  fast  to  a  similar 
abutment  at  the  other  end,  but  between  the  two  is  carried  by 
guide  sheaves  across  the  bridge,  so  that  its  two  ends  are  at  the 
diagonal  corners  of  the  space  enclosed  by  the  tracks,  and  the  two 
ropes  thus  pass  one  another  upon  the  bridge. 

If,  now,  lateral  pressure  be  applied  to  the  bridge,  tending  to 
move  it  longitudinally  in  either  direction,  it  is  still  free  to  move,  the 
guide  sheaves  D,  E,  F,  F  rolling  upon  the  fixed  cords  X  and  Y  as 
the  bridge  moves  along.  If  the  propelling  power  be  applied  directly 
in  the  center  of  the  bridge,  and  if  the  weight  of  the  bridge  and 
its  load  be  divided  equally  between  the  two  end-trucks,  the  bridge 
will  move  in  parallelism  with  its  tracks  without  any  tendency  to 
get  out  of  square  or  to  cramp,  and  no  squaring  device  is  needed. 
If,  however,  the  propelling  power  be  applied  at  some  other  point 
than  at  the  center,  as,  for  instance,  at  the  point  indicated  by  the 
arrow  M,  the  right  hand  end  of  the  bridge  will  tend  to  move 
more  easily  and  more  rapidly  than  the  opposite  end  ;  particularly 
if  it  should  happen  that  the  load  carried  by  the  bridge  rested  at 


56  A    Treatise  on  Cranes. 

the  time  at  or  near  the  left  hand  end  of  the  bridge.  This 
increased  resistance  to  traction  at  the  left  hand  end  of  the  bridge 
may  be  represented  by  the  arrow  N,  acting  in  a  direction  contrary 
to  the  force  at  M,  the  combined  result  being  a  tendency  to  rotate 
or  twist  the  bridge  upon  its  tracks.  If  we  assume  that  the  force 
applied  at  M  be  sufficient  to  move  the  bridge  one  foot  forward, 
it  will  be  seen  that  the  guide  sheave  E  will  be  moved  correspond- 
ingly, and  that  in  doing  so  a  length  of  the  rope  X  equal  to  the 
amount  of  travel  of  the  bridge  must  be  passed  around  the  guide 
sheave  E  in  the  direction  of  the  arrow  S.  The  length  of  cord 
required  for  this  must  of  course  be  drawn  from  that  portion  of  the 
rope  X  located  between  the  sheaves  E  and  F,  and  in  like  manner, 
therefore,  an  equal  amount  must  be  supplied  by  the  length  of  the 
cord  X  which  is  located  between  the  sheave  F  and  the  abutment 
X'.  But  this  latter  can  only  be  obtained  by  the  movement  of  the 
sheave  F  a  corresponding  distance,  namely  one  foot,  towards  the 
point  X' ;  from  which  it  follows  that  a  force  acting  to  move  the 
bridge  one  foot  forward  at  and  in  the  direction  of  the  arrow  M, 
must  produce  a  corresponding  and  equal  force,  acting  through 
the  guide  sheave  F  and  the  cord  X,  to  pull  the  opposite  end  of 
the  bridge  an  equal  distance  in  the  same  direction,  thus  neutral- 
izing the  resistance  indicated  by  the  arrow  N.  Should  the  power 
be  applied  at  the  point  and  in  the  direction  indicated  by  the  arrow 
N,  the  same  result  will  ensue  in  the  reverse  order,  the  cord  X  and 
pullies  F  and  E  acting  to  overcome  the  resistance  M.  So,  also, 
should  the  force  be  applied  at  the  point  M,  but  in  a  direction 
contrary  to  that  above  supposed,  the  parallelism  of  the  bridge 
with  its  tracks  will  be  preserved  by  the  cord  Y,  acting  around  the 
sheaves  D  and  F  in  a  manner  precisely  similar  to  the  action  of 
the  cord  X,  as  above  explained. 

It  thus  follows  that,  by  means  of  the  two  cords  X  and  Y,  and 
the  four  sheaves  D,  E,  F,  F,  the  bridge  is  kept  always  square  to 
its  tracks,  and  compelled  to  move  in  perfect  parallelism  with 
them,  irrespective  of  the  point  at  which  the  propelling  power  is 
applied,  and  independently  of  the  different  resistance  to  traction 
offered  by  the  trucks  at  the  opposite  ends  of  the  bridge,  which 
may  result  from  inequality  of  loads  or  from  any  other  causes. 


Crane  Details. — Squaring  Device.  57 

The  extreme  simplicity  of  this  device  in  only  equaled  by  the 
absolute  perfection  with  which  it  performs  its  work.  A  light 
wire  rope,  of  %  or  fe  inch  diameter,  is  amply  sufficient  for 
squaring  the  largest  bridge,  and  is  also  available  for  propelling  it, 
in  the  manner  explained  hereafter.  The  system  is  equally 
applicable  to  bridges  of  large  or  small  capacity,  and  of  short  or 
wide  span.  It  is  already  in  use  in  cranes  of  25  tons  capacity,  and 
of  more  than  70  feet  span.  Its  parts  are  few  and  simple,  and  the 
motions  slow,  corresponding  with  the  speed  of  the  bridge,  so  that 
the  wear  of  the  parts  is  inappreciable.  The  device  is  equally 
applicable  to  machines  for  operation  by  hand  or  by  power,  and 
its  compactness  and  simplicity  are  in  striking  contrast  to  the 
devices  previously  used,  which  latter  have  usually  consisted  of 
long  transverse  shafts,  with  gearing  in  both  trucks,  and,  for  large 
cranes,  a  longitudinal  rack  adjacent  to  each  of  the  side  tracks, 
and  of  equal  length. 


A    Treatise  on  Cranes. 


BRIDGE    MOVING    DEVICE    FOR    TRAVELING    CRANES. 

The  mechanism  shown  in  Fig.  22  below  comprises  the  bridge 
squaring  device  described  in  the  preceding  chapter,  with  the 
addition  of  a  grip  wheel  applied  to  each  of  the  fixed  squaring 
cords  X  and  Y,  so  that  they  may  be  seized  or  gripped  and 
thereby  made  available  for  pulling  the  bridge  in  either  direction 
desired. 


FIG.  22. -Device  for  Squaring  and  Propelling  Bridges. 


In  Fig.  22  the  bridge  B  rests  and  moves  upon  the 
longitudinal  tracks  AA,  and  is  maintained  in  parallelism  with 
them  by  means  of  the  fixed  squaring  cords  X  and  Y,  as  explained 


Crane  Details. — Bridge  Moving  Device.        59 

before.  Attached  to  the  right  hand  end  of  the  bridge,  and,  for" 
convenience,  located  beneath  it,  is  a  frame  carrying  a  shaft  upon 
which  are  fixed  the  three  wheels  V,  P  and  V.  The  wheel  P, 
which  is  fixed  to  the  shaft  midway  between  the  wheels  V  and  V, 
carries  the  endless  hand  chain  or  rope  Q,  which  reaches  to 
within  a  convenient  distance  of  the  floor  below.  The  peripheries 
of  each  of  these  wheels  contains  a  V-shaped  groove  of  such  form 
that  the  rope,  in  passing  around  the  wheel,  presses  into  it  without 
touching  its  bottom,  and  is  thus  firmly  gripped  between  the  con- 
verging sides  of  the  groove,  so  that  if  the  grip  wheels  are  rotated 
they  tend  to  pull  the  rope  passing  around  them  in  one  direction 
or  the  other,  according  to  the  direction  in  which  they  are  turned. 

Attached  to  the  bridge,  immediately  over  the  wheels  above 
referred  to,  are  guide  sheaves  by  which  the  two  fixed  cords  X  and 
Y  are  deflected  downward  and  into  engagement  with  the  grip 
wheels  V  and  V7.  The  cord  Y  passes  over  its  guide  sheaves 
directly  to  and  from  the  grip  wheel  V,  while  the  cord  X,  on  the 
contrary,  in  passing  to  and  from  the  grip  wheel  V  is  crossed.  It 
follows,  therefore,  that  the  rotation  of  the  grip  wheels  V  and  V 
in  the  same  direction  causes  opposite  parts  of  the  cords  X  and  Y 
to  be  pulled.  If  now  the  hand  rope  Q  be  pulled  so  as  to  rotate 
the  shaft  carrying  the  several  grip  wheels  in  the  direction  of  the 
arrow  L,  the  grip  wheel  V  will  be  caused  to  pull  that  part  of  the 
cord  Y  which,  after  passing  around  the  sheave  D,  is  secured  to 
the  wall  at  Y',  while  at  the  same  time  the  grip  wheel  V,  by  reason 
of  the  crossing  of  the  cord  X  as  it  leads  on  to  it,  will  be  caused 
to  pull  upon  that  part  of  the  cord  X  which,  after  passing  around 
the  sheave  F,  is  made  fast  to  the  wall  at  X'.  It  will  thus  be  seen 
that  the  rotation  of  the  shaft  in  the  direction  of  the  arrow  L  will 
cause  an  equal  and  simultaneous  pull  to  be  exerted  from  the 
two  ends  of  the  bridge  upon  the  abutments  X'  and  Y',  and  the 
bridge  will  accordingly  be  propelled  or  pulled  in  the  direction  of 
the  arrow  M. 

In  considering  the  action  of  this  apparatus  it  is  to  be  noted 
that  all  the  features  of  the  squaring  device  illustrated  in  Fig.  21, 
and  already  described,  are  fully  and  effectively  retained,  while 
at  the  same  time  they  are  further  utilized  for  the  additional 


60  A    Treatise  on  Cranes. 

purpose  of  propelling  the  bridge  longitudinally,  the  additional 
mechanism  required  for  this  purpose  being  very  simple.  More- 
over, the  action  of  the  propelling  mechanism  is  such  as  to  simul- 
taneously pull  each  end  of  the  bridge  in  the  same  direction,  at 
the  same  time  and  at  equal  speeds,  so  that  it  has  no  tendency  to 
strain  the  bridge  out  of  squareness  with  its  tracks. 

For  purposes  of  illustration,  the  mechanism  illustrated  by 
Fig.  22  is  of  the  simplest  possible  form,  with  all  details  removed 
except  such  as  are  essential  to  a  clear  understanding  of  the  action 
of  the  squaring  and  moving  devices. 


Crane  Details. — Moving  Devices.  61 


SQUARING,   AND    BRIDGE    AND    TROLLEY    MOVING    DEVICE 
FOR    TRAVELING    CRANES. 

In  Fig.  21  has  been  shown  the  Weston  system  of  fixed  wire 
cords  as  arranged  to  constitute  a  simple  squaring  device  for  the 
bridge  of  a  traveling  crane.  In  Fig.  22  the  same  device  is 
illustrated  with  additional  provision  by  means  of  which  it  is 
utilized  for  propelling  the  bridge  longitudinally  upon  its  tracks, 
In  Fig.  23  (next  page)  is  shown  a  third  application  of  the  system 
which,  while  retaining  both  of  the  functions  previously  described, 
embodies  the  additional  one  of  provision  for  causing  the  travel 
of  the  trolley  upon  the  bridge  in  either  direction  desired. 

In  Fig.  23  the  bridge  B  rests  and  moves  upon  the  longitudinal 
tracks  AA,  and  is  maintained  in  parallelism  with  them  by  means 
of  the  fixed  squaring  cords  X  and  Y,  as  explained  before. 
Moving  transversely  upon  the  bridge  is  the  trolley  T,  from 
which  the  load  is  suspended.  Upon  each  side  of  the  trolley  is  a 
grip  wheel  V  V,  over  which  the  cords  X  and  Y  are  caused  to 
pass  by  the  small  guide  sheaves  UU  on  the  trolley.  The 
peripheries  of  the  several  guide  sheaves  are  all  provided  with  a 
concave  groove  of  a  radius  slightly  greater  than  that  of  the  wire 
rope,  so  that  the  latter  passes  freely  over  them  without  binding. 
The  periphery  of  the  grip  wheels  V  V,  on  the  other  hand, 
contains  a  V-shaped  groove  of  such  form  that  the  wire  rope,  in 
passing  around  the  wheel,  presses  into  the  groove  without 
touching  its  bottom,  and  is  thus  firmly  gripped  between  the 
converging  sides  of  the  groove,  so  that  if  the  grip  wheels  are 
rotated  they  tend  to  pull  the  rope  passing  around  them  in  one 
direction  or  the  other,  according  to  the  direction  in  which  they 
are  turned. 

If  now  the  grip  wheels  V  and  V  be  both  rotated  simulta- 
neously and  at  equal  speeds  in  the  direction  of  the  arrow  L,  it  is 
evident  that  they  will  each  draw  or  pull  upon  that  portion  of  each 
of  the  ropes  X  and  Y  which  lies  between  the  trolley  and  the  right 


62 


A    Treatise  on  Cranes. 


hand  end  of  the  bridge.  But  as  the  rope  Y  is  attached  to  a  fixed 
abutment  at  Y',  and  the  corresponding  end  of  the  rope  X  to  a 
similar  abutment,  they  cannot  be  drawn  towards  the  trolley,  and 
therefore  the  trolley  must  follow  them,  so  that  the  simultaneous 
rotation  of  the  two  grip  wheels  in  the  direction  of  the  arrow  L 
tends  to  move  the  trolley  in  the  direction  of  the  arrow  R,  the 


FIG.  23. — Device  for  Squaring  and  for  Propelling  Bridges  and  Trolleys. 

bridge  remaining  stationary.  A  reverse  motion  of  the  grip 
wheels  V  and  V  would  of  course  tend  to  move  the  trolley 
in  a  direction  contrary  to  the  arrow  R.  If,  however,  the  grip 
wheel  V  be  rotated  in  the  direction  of  the  arrow  L,  and 
the  grip  wheel  V  in  the  contrary  direction,  the  effect  of  the 
former  will  be  to  pull  upon  the  cord  Y,  and  through  it  upon 


Crane  Details. — Moving  Devices.  63 

its  abutment  Y',  while  the  effect  of  the  latter  will  be  to  pull 
upon  the  cord  X,  and  through  it  upon  its  abutment  X'.  The 
grip  wheels  being  thus  rotated  in  contrary  directions,  but 
at  equal  speeds,  the  bridge  will  be  propelled  towards  the  wall 
W  by  a  direct  pull  upon  the  fixed  abutments  X'  and  Y'  trans- 
mitted through  the  cords  X  and  Y.  It  is  immaterial,  however, 
that  the  grip-wheels  be  rotated  with  equal  power  and  at  equal 
speeds,  for  any  inequality,  either  of  the  power  applied  or  the 
resistance  encountered  by  the  trucks,  simply  brings  into  play  the 
squaring  properties  of  the  fixed  cords,  and  distributes  the  pro- 
pelling power  equally  between  the  opposite  ends  of  the  bridge. 
If  only  one  of  the  grip-wheels  be  rotated,  as,  for  example  the  wheel 
V  in  the  direction  of  the  arrow  L,  the  effect  is  to  pull  or  draw 
that  portion  of  the  cord  Y  which  lies  between  the  trolley  and  the 
abutment  Y'.  The  effect  of  this,  if  the  trolley  moves  much  more 
easily  than  the  bridge,  will  be  to  draw  the  trolley  towards  the 
right  hand  end  of  the  bridge,  the  latter  remaining  stationary.  If 
the  bridge  moves  more  easily  than  the  trolley,  the  effect  will  be 
to  draw  the  bridge  towards  the  wall  W,  the  trolley  remaining 
stationary.  If  the  resistance  of  both  bridge  and  trolley  be  equal, 
the  motion  will  be  equally  divided  between  them,  so  that,  if  one 
foot  of  the  rope  be  passed  over  the  grip  wheel  V  by  its  rotation, 
the  trolley  will  move  six  inches  upon  the  bridge,  and  the  bridge 
move  six  inches  upon  its  tracks,  the  resultant  motion  of  the  load 
being  a  diagonal  of  45  degrees.  Under  all  conditions  the 
squaring  device  performs  its  function  equally  well,  and  insures 
the  parallelism  of  the  bridge  with  its  tracks  at  all  times  and  under 
all  inequalities,  either  of  load  or  of  resistance. 

The  mechanism  illustrated  in  Fig.  23  is  purposely  of  a  very 
simple  form  in  order  to  more  clearly  illustrate  the  action  of  the 
device.  In  traveling  cranes  for  operation  by  hand  the  grip 
wheels  are  usually  rotated  by  endless  ropes  or  chains,  operated 
by  the  workman  from  the  floor  below,  while  in  cranes  operated 
by  power  the  motive  force  is  made  available  for  rotating  the  grip- 
wheels  through  the  instrumentality  of  Weston-Capen  Clutches, 
operated  by  suitable  hand  levers. 

The  above  illustrations  and  descriptions  will,  it  is  hoped, 


64  A    Treatise  on  Cranes. 

make  perfectly  clear  the  great  simplicity  and  absolute  efficiency 
of  the  Western  system  of  fixed  cords  for  squaring  and  propelling 
the  bridges  of  traveling  cranes.  As  already  stated,  the  invention 
is  equally  applicable  to  cranes  operated  by  hand  or  by  power. 
It  has  long  since  passed  from  the  experimental  stage  and  is  now 
in  daily  use  upon  numerous  cranes  of  various  types  and  of  all 
capacities.  Under  all  conditions  it  is  found  to  do  its  work  cer- 
tainly, quietly  and  perfectly.  Its  introduction  marks  a  new 
departure  in  the  construction  of  traveling  cranes,  and  by  reason 
of  its  simplicity  and  economy  of  construction  greatly  enlarges 
the  adaptability  of  the  traveling  crane,  and  makes  it  available  for 
numerous  uses  to  which  it  has  not  heretofore  been  possible  to 
apply  it. 


Crane  Details. —  Trolley  Traveling  Mechanism.  65 


TROLLEY    TRAVELING    MECHANISM. 

In  jib,  traveling  and  other  cranes  provided  with  trolleys, 
some  mechanism  is  necessary  to  effect  the  longitudinal  motion  of 
the  latter.  This  may  be  accomplished  by  a  rack  and  pinion,  or 
by  an  endless  chain  or  rope  attached  to  the  trolley  and  operated 
by  a  driving-wheel  at  one  end,  with  a  suitable  guide  sheave  for 
returning  it  at  the  opposite  end.  All  devices  of  this  kind  are 
entirely  distinct  from  the  hoisting  gear  of  the  crane  and  are 
operated  independently.  Under  some  conditions  a  separate 
mechanism  for  this  purpose  is  desirable,  but  usually  this  is  not  the 
case.  We  illustrate  below  the  system  adopted  in  most  of  the 
Weston  Cranes  which,  as  will  be  seen,  effects  the  motion  of  the 
trolley  by  means  of  the  devices  employed  for  hoisting  and  lower- 
ing, and  thus  obviates  the  need  of  any  separate  mechanism. 

Fig.  24  represents  a  Weston  Jib  Crane  with  combined 
hoisting  and  traversing  gear.  Referring  to  the  figure,  A,  B  and 
C  are  respectively  the  jib,  mast  and  brace  of  a  jib  crane.  D  is 
the  running  block,  J  the  trolley  carrying  the  sheaves  which  form 
the  upper  block,  F,  G  and  H  guide  sheaves  by  which  the  two 
parts  of  the  chain  are  directed  to  the  two  housings  attached  to 
each  side  of  the  mast  near  its  base,  and  containing  the  operating 
mechanism.  Each  of  these  latter  is  a  complete  and  independent 
hoisting  machine,  operated  respectively  by  the  cranks  or  handles 
L  and  M,  the  shafts  of  which  extend  through  the  housings,  so 
that  cranks  may  be  applied  upon  either  or  both  ends  of  each  shaft. 
The  chain  X  passes  from  the  left  hand  housing  over  the  guide 
sheave  G,  then  around  the  guide  sheave  F,  and  so  to  the 
trolley  J,  where  it  passes  over  another  sheave  and  extends  down- 
ward to  the  block  D.  In  like  manner,  the  other  part  Y  of  the 
chain  passes  from  its  housing  over  the  sheave  H  directly  to  the 
trolley,  and  so  down  to  the  block.  By  turning  the  crank  M  so 
as  to  haul  in  the  part  Y  of  the  chain,  the  load  will  be  raised,  and, 
in  like  manner,  by  turning  the  crank  L  so  as  to  haul  in  the  part 


66 


A    Treatise  on  Cranes. 


X  of  the  chain,  the  load  will  be  raised.  By  simultaneously 
turning  both  cranks  so  as  to  haul  in  both  parts  of  the  chain,  the 
load  will  be  raised  at  double  speed.  By  rotating  either  or  both 
of  the  cranks  in  the  opposite  direction,  the  opposite  motions  will 
be  effected,  and  the  load  will  be  lowered  at  single  or  double 
speed.  By  slipping  both  pinions  on  their  shafts  so  that  they 


FIG.  24. — Mechanism  for  Moving  Trolleys. 

engage  with  the  large  spur  wheel  N  between  them,  motion  of 
one  pinion  will  be  communicated  to  the  other  at  an  equal  speed, 
but  in  a  contrary  direction,  the  result  of  which  will  be  to  cause  the 
part  Y,  for  example,  to  be  hauled  in  and  the  part  X  to  be  paid 
out  (as  indicated  by  the  arrows  on  the  cut)  at  exactly  equal 
speeds.  The  consequence  of  this  will  be  to  cause  the  trolley  J  to 


Crane  Details. —  Trolley  Traveling  Mechanism.  67 

be  pulled  toward  the  mast  by  the  part  Y  of  the  chain,  while  at  the 
same  time  the  part  X  of  the  chain  will  be  released  or  paid  out  at 
the  same  speed,  and  thus  oppose  no  resistance  to  the  inward 
motion  of  the  trolley.  During  this  time  the  parts 'of  the  chain 
lying  below  the  trolley,  and  between  it  and  the  block  D,  are  not 
disturbed,  so  that  the  load  remains  suspended  upon  them,  and  no 
unnecessary  friction  or  wear  of  the  chain  is  caused  by  needless 
rendering  of  the  chains  over  the  sheaves  in  the  trolley  and  block. 
It  will  thus  be  seen  that,  when  it  is  desired  to  move  the  trolley 
in  either  direction,  the  two  parts  of  the  chain  which  lead  from 
the  trolley  back  to  the  operating  mechanism,  are  utilized  to  effect 
its  motion,  thus  dispensing  with  the  need  of  any  separate 
mechanism  for  this  purpose,  while  at  the  same  time  the  rest  of 
the  chain  remains  stationary  and  is  not  subject  to  wear. 

In  traveling  cranes  the  same  result  is  obtained,  save  that,  in 
some  cases,  the  horizontal  parts  of  the  chain  pass  directly  from 
the  trolley  to  the  operating  mechanism  without  being  deflected 
by  guide  sheaves,  although  in  most  cases  it  is  found  best  to  place 
the  mechanism  beneath  the  bridge,  in  which  case  the  action  is 
identical  with  that  above  explained,  except  that  the  operating 
mechanism  is  close  to  the  guide  sheaves  G  and  H  instead  of  at 
some  distance  below  them,  as  in  the  case  of  a  jib  crane.  In 
power  cranes,  of  whatever  type,  this  arrangement  is  equally 
applicable,  the  only  difference  being  that  the  several  motions  are 
effected  by  power,  transmitted  through  suitable  clutches,  instead 
of  by  manual  effort  applied  to  the  cranks  or  hand  chains. 

A  prominent  and  most  valuable  feature  of  this  construction 
consists  in  the  even  distribution  of  wear  over  all  parts  of  the 
chain.  Referring  to  Fig.  24,  it  may  be  explained  that  the  two 
parts  X  and  Y  of  the  chain,  after  passing  through  the  housings 
at  the  foot  of  the  mast,  enter  a  suitable  box  or  receptacle,  and  are 
there  united,  so  that  the  chain  is  endless,  although  for  clearness  of 
description  its  two  parts  or  sides  are  distinguished  in  the  foregoing 
description  by  the  letters  X  and  Y.  It  is  found  in  practice  that,  in 
using  cranes  thus  constructed,  the  operator  frequently  changes 
from  one  crank  to  the  other,  so  that  when  hoisting,  the  part  Y,  for 
example,  will  be  hauled  in,  while,  when  it  is  desired  to  lower  or 


68  A    Treatise  on  Cranes. 

to  cause  travel  of  the  trolley,  the  part  X  may  be  paid  out,  and  in 
this  way  the  whole  length  of  the  chain  is  gradually  passed  through 
the  operating  mechanism  and  each  of  its  links  subjected  to  equal 
wear.  No  special  attention  need  be  given  to  the  attainment  of 
this  end,  as  the  varying  requirements  of  use  secure  its  attainment 
without  any  attention  on  the  part  of  the  operator,  and  all  parts  of 
the  chain  are  ultimately  subjected  to  practically  equal  wear. 
Where  the  chain  is  wound  upon  a  drum,  on  the  contrary,  certain 
parts  of  the  chain  will  necessarily  receive  most  of  the  wear,  and 
will  become  weakened  and  unsafe  while  the  rest  of  the  chain 
may  be  perhaps  almost  unimpaired.  This  equal  distribution  of 
wear  over  the  entire  length  of  the  chains,  which  is  accomplished 
by  the  Weston  system  of  construction,  thus  gives  great  durability 
to  the  chains,  and  proportionately  increases  their  safety.  It  may 
be  noted  also  that,  as  the  parts  of  chain  between  the  trolley  and 
the  block  are  not  disturbed  during  the  motion  of  the  trolley,  a 
much  smoother  and  quieter  action  occurs  than  when  these  parts 
of  the  chain  are  compelled  to  render  over  the  sheaves,  as  is  the 
case  with  the  ordinary  construction.  This  feature  is  of  particular 
value  in  foundry  work,  and  is  valuable  in  all  cases  as  tending  to 
diminish  the  wear  upon  the  chain,  and  thus  prolong  its  life. 


Crane  Details. — Gearing  of  Jib  Cranes.       69 


GEARING    OF    JIB    CRANES   FOR    OPERATION    BY    HAND. 

The  mode  of  operating  the  hoisting  and  traversing  mechanism 
of  the  larger  sizes  of  the  Weston  Jib  Cranes  is  fully  explained  in 
the  preceding  article.  The  details  of  the  gearing  whereby  these 
several  motions  are  effected  are  as  follows. 


FIG.  25. — Gearing  of  Jib  Crane. 


Fig.  25  is  a  cross-section  taken  at  the  foot  of  the  mast  of  a 
large  jib  crane,  as  illustrated  in  Part  III.     A  is  the  mast,  to  each 


A   Treatise  on  Cranes. 


side  of  which  is  bolted  a  housing  containing  the  gearing  for 
operating  the  two  parts  X  and  Y  of  the  main  hoisting  chain. 
Each  of  these  housings  is  provided  with  a  horizontal  shaft, 
revolving  upon  which  is  the  worm  wheel  P,  the  hub  of  which 
covers  the  entire  length  of  the  pin  or  shaft  between  its  bearings. 
Fitted  over  the  hub  of  this  wheel,  and  bolted  securely  to  it,  is  the 
pocketed  chain  wheel  R,  provided  with  the  chain  stripper  V,  and 
also  with  a  suitable  chain  guide  S,  substantially  in  the  manner 
illustrated  in  Fig.  i.  The  chain  wheel  is  made  separately  from 
the  worm  wheel  to  admit  of  easy  removal  and  renewal  when  worn 
out.  Referring  now  to  the  right  hand  housing  in  the  cut,  O  is  the 
crank  shaft  extending  through  the  housing  at  right  angles  to  the 
worm  wheel  shaft  above.  Q  is  the  worm,  fitted  upon  the  shaft 
O  at  its  center,  and  gearing  into  the  worm  wheel  P.  K  is  a  spur 
pinion,  fitted  to  one  end  of  the  shaft  O,  and  capable  of  sliding 
longitudinally  thereon.  T  is  a  small  guide  sheave  over  which 
the  slack  of  the  chain  falls  after  passing  around  the  lower  semi- 
circumference  of  the  chain  wheel  R.  The  arrangement  of  the 
opposite  or  left  hand  housing,  and  its  contained  gearing,  is  the 
same  as  that  just  described. 

Fig.  26  is  a  detail  view  of  one  of 
the  chain  wheels  R,  with  the  chain 
guide  S  and  stripper  V,  showing  the 
manner  in  which  the  chain  is  guided 
during  its  contact  with  the  wheel,  and 
the  provision,  by  means  of  the  stripper 
V,  for  compelling  it  to  leave  the 
wheel  R  at  the  proper  point  in  which- 
ever direction  the  wheel  is  being  turned. 
The  slack  part  of  the  chain,  after  pass- 
ing over  the  guide  sheave  T,  falls  into 
a  receptacle  between  the  housings  at  the  foot  of  the  mast.  The 
chain  being  endless,  the  two  parts  X  and  Y  come  together  in  the 
receptacle  just  referred  to,  and  are  there  united,  the  amount  of 
slack  chain  contained  in  the  box  varying  with  the  position  of 
the  running  block. 

Fig.   27  is  a  horizontal   cross-section  taken  through   both 


FIG.  26. 


Crane  Details. — Gearing  of  Jib  Cranes.       71 

housings  and  the  mast  of  the  crane,  the  several  parts  being  desig- 
nated by  the  same  letters  as  in  Fig.  25.  M  is  a  shaft  parallel  to 
the  crank  shafts  O  and  N,  extending  through  the  mast  and 
carrying  at  one  end  the  large  spur  wheel  L.  The  pinions  J  and 
K,  as  previously  explained,  are  arranged  to  slip  upon  their  shafts 
so  as  to  bring  them  into  or  out  of  coincidence  with  the  interme- 
diate wheel  L.  As  shown  in  Fig.  27,  the  pinion  K  is  engaged 
with  the  wheel  L,  and  the  pinion  J  is  disengaged.  If  now  the 
crank  be  applied  to  the  shaft  N  and  turned  in  the  proper  direction, 


FIG.  27. — Gearing  of  Jib  Crane. 

the  chain  X  will  be  hauled  in  and  the  load  raised.  The  same 
effect  will  result  from  rotation  of  the  shaft  O.  If  both  be  turned 
simultaneously,  hoisting  will  be  effected  at  double  speed.  By 
applying  the  crank  to  the  shaft  M,  motion  will  be  communicated, 
through  the  wheel  L  and  pinion  K,  to  the  shaft  O,  and  hoisting 
will  occur  at  a  rapid  speed  proportionate  to  the  relative  diameters 
of  the  wheels  L  and  K.  Three  speeds  are  thus  obtained  for 
hoisting,  all  of  which  are  equally  applicable  to  lowering  by 
reversing  the  motion  of  the  cranks. 


72  A    Treatise  on  Cranes. 

To  effect  travel  of  the  trolley,  in  the  manner  explained  in 
the  preceding  article,  both  pinions  J  and  K  are  slipped  into 
engagement  with  the  wheel  L.  By  then  turning  either  of  the 
shafts  N  or  O  in  the  proper  direction,  one  part  of  the  hoisting 
chain,  X  for  example,  will  be  hauled  in,  and  the  opposite  part,  Y, 
paid  out  at  equal  speeds,  the  effect  of  which  is  to  cause  the 
trolley  to  move  horizontally  upon  the  jib.  By  applying  the 
crank  to  the  shaft  M,  these  motions  are  accelerated,  and  a  rapid 
movement  of  the  trolley  results. 

Two  cranks  are  furnished  with  each  crane,  and  it  is  to  be 
noted  that  the  construction  admits  of  the  employment  of  both 
cranks  upon  any  one  of  the  shafts  M,  N,  or  O,  so  that  the  entire 
energy  of  all  the  men  employed  upon  the  crane  is  transmitted 
through  that  shaft,  while,  if  more  rapid  action  is  desired,  one  of 
the  cranks  may  be  placed  upon  the  right  hand  end  of  the  shaft 
N  and  the  other  upon  the  opposite  or  left  hand  end  of  the  shaft 
O.  In  either  case  the  two  shafts,  being  on  opposite  sides  of  the 
crane,  do  not  in  any  way  interfere  with  one  another,  and  are 
thus  always  available  for  the  full  number  of  men  who  can 
effectively  be  employed  upon  them. 

The  compactness  and  simplicity  of  this  mechanism  will  be 
apparent  from  the  foregoing  description.  The  entire  operating 
mechanism  of  the  crane  consists  of  two  worm  wheels  and  worms, 
and  of  the  spur  wheel  L  with  its  two  pinions.  The  worm  wheels 
and  worms  are  entirely  contained  within  the  two  housings,  the 
upper  parts  of  which  latter  are  arranged  to  lift  off  to  give  access 
to  the  gearing.  Each  of  the  worms  runs  in  an  oil  well,  thus 
insuring  perfect  lubrication,  and  each  of  these  wells  is  provided 
with  a  drainage  tap  at  the  bottom  to  draw  off  the  lubricant  when 
desired. 


Crane  Details. — Gearing  of  Traveling  Cranes.  73 


GEARING    AND    CLUTCHES   OF    POWER    TRAVELING    CRANES. 

As  stated  elsewhere,  the  main  chains  of  the  Weston  Power 
Traveling  Cranes  are  arranged  in  substantially  the  same  manner 
as  on  the  jib  crane  illustrated  and  described  in  the  two  preceding 
articles.  Briefly  described,  the  arrangement  is  as  follows  :  The 
chain  is  endless,  and  after  passing  over  the  sheaves  in  the  bottom 
block  and  in  the  trolley,  one  of  its  parts  is  carried  directly  to  the 
crab  containing  the  operating  mechanism,  while  the  other  part 
passes  first  in  the  opposite  direction  to  the  other  end  of  the 
bridge,  where  it  is  returned  around  a  guide  sheave,  and  thence 
carried,  parallel  to  the  first  part,  back  to  the  crab.  The  two 
parts  of  the  chain  thus  enter  the  crab  side  by  side.  Hoisting  is 
effected  at  one  speed  by  pulling  in  either  part  of  the  chain,  and 
at  double  speed  by  pulling  in  both  parts  simultaneously.  Lower- 
ing is  effected  also  at  two  speeds,  by  the  contrary  motions.  By 
hauling  in  one  part  and  paying  out  the  other  simultaneously,  at 
equal  speeds,  the  trolley  is  caused  to  travel  on  the  bridge.  In 
order  to  effect  the  several  operations  of  the  crane,  therefore,  it  is 
necessary  that  the  mechanism  should  be  capable  of  hauling  in  or 
paying  out  either  one  of  two  separate  chains  or  ropes  indepen- 
dently of  the  other,  and  of  paying  out  or  hauling  in  both  ropes 
or  chains  simultaneously,  and  also  that  it  should  be  capable  of 
paying  out  the  one  and  hauling  in  the  other  simultaneously  and 
at  equal  speeds.  The  mechanism  by  which  these  apparently 
complex  movements  are  obtained  is  illustrated  in  the  following 
figures. 

Fig.  28  is  a  plan  or  top  view  of  the  reversing  mechanism  of 
a  Weston  Power  Traveling  Crane,  with  the  surrounding  crab 
frame  or  housing  removed  so  as  to  clearly  expose  the  mechanism. 
A  is  the  primary  shaft,  carrying  the  rope  driving  wheel  B,  by 
means  of  which  it  is  constantly  driven  in  one  direction  and  at 
uniform  speed.  C  and  D  are  the  worm  shafts,  lying  parallel 
with  A  and  slightly  below  it.  The  latter  shafts  carry  respectively 


74 


A    Treatise  on  Cranes. 


the  worms  M  and  K,  gearing  into  the  worm  wheels  N  and  L.   B 
The  latter  rotate  upon  a  transverse  shaft  Z,  and  have  screwed  to 


FIG.  28. — Top  View  of  Reversing  Mechanism. 

their  respective  inner  sides  the  pocketed  chain  wheels  X  and  Y 
by  means  of  which  the  two  parts  of  the  chain  are  to  be  hauled  in 

or  paid  out. 

J 


FIG.  29. — Side  Elevation  of  Reversing  Mechanism. 

Fig.  29  is  a  side  elevation  of 
the  mechanism  shown  in  Fig.  28, 
similar  letters  of  reference  indicat- 
ing similar  parts  in  both  views. 

Fig.  30  is  an  end  view  of  the 
three  shafts  A,  C  and  D,  with  their 
several  gear  wheels.  By  reference 
to  each  of  the  three  views  above  given,  the  following 


Crane  Details. — Gearing  of  Traveling  Cranes.  75 


FIG.  30.— End  View  of  the  Three  Shafts  of  the  Re- 
versing Mechanism  and  their  Connecting  Gears. 


explanation  of  the  several  parts  of  the  mechanism  will  be  easily 
followed. 

Attached  to  the  shaft  A  and  revolving  with  it  is  the  spur 
pinion  J.  On  the  shaft  D  are  two  spur  wheels  F  and  H,  and  on 
the  shaft  C  two  corresponding  spur  wheels  G  and  I.  Each  of  these 
four  spur  wheels  can  revolve  freely  on  its  shaft,  or  the  shaft 

within  the  wheels,  without 
any  motion  being  communi- 
cated from  one  to  the  other. 
Cast  in  one  piece  with  the 
wheel  F  is  the  pinion/,  and 
with  the  wheel  G  is  the  pin- 
ion g.  The  spur  pinion  J  on 
the  driving  shaft  A  is  always 
in  gear  with  the  pinions  / 
and  .if. 

By  reference  to  Fig.  30 
it  will  be  seen  also  that  the 
spur  wheels  F  and  I  are  always  engaged  together,  and,  in  like 
manner,  the  spur  wheels  G  and  H,  whence  it  follows  that  the 
wheels  F  and  I  are  always  running  in  contrary  directions,  as  are 
also  the  wheels  G  and  H,  and,  therefore,  that  F  and  G  must  run 
in  like  directions,  and  H  and  I  in  like  directions,  but  contrary 
to  F  and  G. 

We  thus  have  on  each  of  the  shafts  C  and  D  two  wheels  or 
pinions,  one  of  which  rotates  to  the  right  and  the  other  to  the 
left,  but  both  revolving  freely  on  their  shafts,  so  that  no  motion 
is  communicated  to  the  latter. 

Within  each  of  the  four  wheels  F,  G,  H  and  I  is  a  Weston- 
Capen  Clutch  (see  page  47),  by  means  of  which  each  of  the  four 
wheels  may  at  will  be  clutched  to  its  shaft,  so  that  the  motion  of 
the  wheel  will  be  imparted  to  the  shaft.  The  clutches  within 
the  wheels  G  and  I  (see  Fig.  28)  are  operated  by  the  shipper  rod 
T,  and  the  clutches  of  the  wheels  F  and  H  by  the  shipper  rod  S. 
The  arrangement  of  these  shipper  rods  is  such  that  each  may  be 
moved  independently  of  the  other,  but  that  the  motion  of  either 
rod  in  a  direction  proper  to  engage  one  of  its  clutches  effects  the 


76  A  Treatise  on  Cranes. 

release  of  its  other  clutch,  and  vice  versa,  so  that  only  one  of  the 
two  revolving  wheels  on  each  of  the  shafts  C  and  D  can  at  any 
given  time  be  clutched  to  its  shaft.  By  a  simple  arrangement  of 
levers  the  operator  is  enabled  to  control  both  shipper  rods,  and 
by  means  of  them  to  cause  the  shafts  C  and  D  to  rotate  in  either 
direction  independently  or  simultaneously,  as  desired,  and  thus 
to  cause  the  chain  wheels  X  and  Y  to  haul  in  or  pay  out  either  or 
both. of  the  two  parts  of  the  chain,  or  to  haul  in  one  part  and  pay 
out  the  other  simultaneously  and  at  equal  speeds.  To  effect 
the  travel  of  the  bridge,  by  means  of  the  fixed  cable  system,  a 
third  shaft  is  attached  to  the  crab  or  housing,  parallel  with  the 
shaft  D  and  provided  with  two  loose  spur  wheels  gearing 
respectively  with  the  wheels  F  and  H,  so  that  they  rotate  in 
opposite  directions.  A  pair  of  Weston-Capen  Clutches,  and  a 
shipper  arrangement  similar  to  that  above  described,  enable 
either  of  these  wheels  to  be  clutched  to  this  third  shaft,  thus 
driving  it  in  either  direction  desired,  and  thereby  moving  the 
bridge.  This  pair  of  clutches  is  controlled  by  a  separate  lever. 
By  means  of  the  two  levers  first  referred  to  six  movements  are 
obtained,  viz.  : 

Hoisting  at  slow  speed  ; 

Hoisting  at  double  speed  ; 

Lowering  at  slow  speed  ; 

Lowering  at  double  speed  ; 

Travel  of  the  trolley  inward  ; 

Travel  of  the  trolley  outward. 

By  means  of  the  third  lever  two  other  movements  are 
obtained,  viz.  : 

Travel  of  the  bridge  to  the  right  ; 
Travel  of  the  bridge  to  the  left. 

In  the  larger  cranes  back  gearing  is  usually  added  in  order 
to  give  a  slower  speed  for  heavy  loads.  This  involves  the 
addition  of  only  one  more  shaft  and  two  small  spur  wheels  with 
clutches,  and  the  back  gearing  is  controlled  by  an  independent 
lever.  This  addition  gives  twice  as  many  speeds  as  before  and 
enables  twice  as  many,  that  is  sixteen,  distinct  movements  to  be 


Crane  Details. — Gearing  of  Traveling  Cranes.  77 

made.      Thus    arranged,    the    machine    has    capacity    for  the 
following  changes  of  movement. 

Hoisting,  four  speeds  ; 

Ldwering,  four  speeds  ; 

Bridge  travel,  in  either  direction,  two  speeds  ; 

Trolley  travel,  in  either  direction,  two  speeds. 

The  entire  mechanism,  by  which  these  sixteen  changes  of 
movement  are  obtained,  is  contained  within  a  crab  or  housing 
which,  in  the  case  of  a  20-ton  crane,  measures  only  24  by  48  by 
31  inches,  and  which  is  attached  permanently  to  the  under  side 
of  the  bridge  at  one  end.  The  compactness,  simplicity  and 
perfect  reliability  of  this  mechanism  can  only  be  fully  appreciated 
by  actual  examination.  By  reason  of  its  compactness  the 
greatest  economy  of  space  is  secured,  and  a  longer  motion  of  the 
trolley,  and  greater  height  of  hoist  at  the  operating  end  of  the 
bridge,  are  obtained  than  is  otherwise  possible.  All  of  the 
important  mechanism  of  the  machine  is  in  this  way  concentrated 
at  the  operating  end,  within  easy  view  and  reach  of  the  operator, 
and  both  the  bridge  and  the  trolley  are  relieved  from  the 
numerous  and  cumbersome  shafts,  gearing  and  other  attachments 
which  have  been  necessary  in  former  types  of  cranes. 


A  Treatise  on  Cranes. 


BRIDGE    TRUCKS. 

The  bridges  of  traveling  cranes  are  supported  at  each  end 
by  trucks  carrying  the  wheels  which  travel  upon  the  longitudinal 
tracks.  The  construction  of  these  trucks  has  been  a  subject  of 
careful  study,  and  as  a  result  the  designs  illustrated  below  have 
been  adopted  in  the  Weston  Cranes. 


FIG.  31.— Truck  for  I-Beam  Bridge. 

Fig.  31  represents  the  end-truck  of  a  bridge  composed  of 
two  solid  I-beams  placed  side  by  side.  This  construction  of 
bridge  is  employed  in  traveling  cranes  in  which  the  span  and  the 
load  to  be  lifted  are  within  limits  which  permit  of  it,  as  explained 
in  the  succeeding  article.  Referring  to  the  cut,  AA  are  the  two 
I-beams  composing  the  bridge,  BB  are  two  cast  iron  brackets,  C 
a  cast  iron  separator  between  the  beams,  and  E  a  bolt  holding 
all  of  these  parts  in  engagement.  The  inner  ends  of  the  brackets 
BB  are  fitted  accurately  to  the  contour  of  the  sides  of  the 
I-beams,  so  that,  when  the  parts  are  drawn  together  by  the  bolt 
E,  the  brackets  are  rigidly  secured  against  rotation  or  displace- 
ment in  any  direction.  The  truck-wheels  DD  are  double-flanged, 
and  are  sufficiently  separated  to  give  a  proper  wheel-base.  Their 
axles  are  secured  to  them  and  turn  with  them,  the  journals 
being  formed  in  the  two  sides  of  the  bracket  B.  The  strains 
resulting  from  a  load  upon  the  bridge  are  resolved  into  compres- 


Crane  Details. — Bridge  Trucks. 


79 


sion  upon  the  upper  portion  of  the  brackets  BB,  which  is  resisted 
by  the  metal  of  the  bracket,  and  into  tension. at  the  bottom, 
which  in  turn  is  carried  by  the  bolt  E.  The  beams  forming  the 
bridge  extend  through  the  truck  to  its  outer  side,  thus  overlap- 
ping the  longitudinal  track,  so  that  the  breakage  of  any  of  the 
parts  of  the  truck  would  merely  result  in  allowing  the  beams  AA 
to  rest  upon  the  track. 


FIG.  32.— Truck  for  Plate  Girder  Bridge. 

In  Fig.  32  is  represented  the  form  of  end-truck  used  in  large 
traveling  cranes,  the  bridges  of  which  are  formed  of  plate 
girders. 

In  this  case  AA  are  the  two  girders  composing  the  bridge, 
and  BB  the  brackets  for  supporting  the  truck-wheels.  In  order 
to  economize  space  between  the  ends  of  the  bridge  and  the  walls  of 
the  building,  the  truck-wheels  DD  are  overhung,  and  their  axles 


8o  A  Treatise  on  Cranes. 

GG  are  extended  to  reach  bearings  in  the  brackets  CC.  FF  are 
separators  between  the  girders  and  in  line  with  each  pair  of 
brackets.  In  this  case,  as  in  the  one  above  described,  the  effect 
of  the  load  is  to  cause  compression  in  the  upper  portions  of  the 
brackets  BB  (which  is  resisted  by  the  metal  composing  the 
brackets),  and  tension  at  the  bottom.  The  latter  strain  is  borne 
by  the  bolt  E,  which  passes  through  both  brackets,  both  girders, 
and  the  separator  F,  and  serves  to  rigidly  hold  all  of  these  several 
parts  in  engagement.  The  upper  ends  of  the  brackets  are  bolted 
through  the  girders  to  the  separator  F  by  smaller  bolts,  as  shown 
in  the  cut,  their  purpose  being  to  securely  locate  the  several 
parts  in  the  proper  relative  positions.  The  strains  caused  by 
the  load  are  chiefly  carried  by  the  brackets  BB,  which  are  much 
heavier  than  those  at  CC,  and  which  are  provided  with  spherical 
bearings  of  bronze,  so  arranged  as  to  permit  the  wheels  to  adapt 
themselves  to  any  irregularities  of  the  track.  It  will  be  seen 
that  the  girders  AA  overlap  the  longitudinal  track,  so  that  any 
failure  of  the  trucks  would  simply  permit  the  bridge  to  rest  upon 
the  tracks. 

The  methods  of  construction  illustrated  above,  while  novel, 
are  believed  to  be  more  simple  and  secure  than  any  heretofore 
employed.  Wrought  iron  is  employed  to  resist  tensional  strains, 
and  the  construction  is  such  that  these  strains  are  parallel  with 
the  axis  of  the  bolt  in  each  case,  and  no  bending  or  sheering 
strains  are  introduced.  The  cast  iron  members  are  so  formed 
as  to  best  resist  the  strains  they  are  subjected  to,  and  the 
construction  throughout  is  exceedingly  simple. 


Crane  Details. — Frames  and  Girders.         81 


FRAMES   AND    GIRDERS. 

For  the  reasons  stated  in  Part  I,  construction  in  iron  has 
been  adopted  almost  exclusively  for  the  frames,  girders,  etc.,  of 
the  Weston  Cranes.  The  great  variety  of  structural  shapes  of 
iron  which  are  now  obtainable,  and  the  increasing  capacity  of  our 
rolling  mills  to  produce  shapes  of  large  area  and  of  great  length, 
have  greatly  simplified  and  cheapened  the  building  of  iron  crane 
frames  and  girders  of  moderate  sizes.  Wherever  the  dimensions 
of  the  work  admit  these  irons  are  employed.  In  larger  machines 
resort  is  had  to  plate  girders,  as  described  below,  while  for  the 
columns  of  large  pillar  cranes  and  similar  machines  cast  iron  in 
single  pieces  is  employed. 

The  frames  of  small  jib  cranes  may  frequently  be  constructed 
by  using  a  single  iron  for  each  of  the  principal  members,  as 
shown  by  the  illustrations  in  Part  III,  in  which  case  the  I-beam 
section  is  found  best.  For  larger  sizes,  say  from  3  tons  upwards, 
a  double  frame,  each  of  the  principal  members  being  composed 
of  two  channel  irons,  is  found  better. 

The  latter  construction  is  shown  in  outline  in  Fig.  33,  in 
which  the  jib  A,  mast  B,  and  brace  C  are  each  composed  of  two 
channel  irons,  separated  sufficiently  to  give  proper  room  for  the 
attachment  of  the  mechanism  and  to  permit  the  main  chains, 
depending  from  the  trolley,  to  pass  between  the  two  irons 
forming  the  jib.  The  best  and  most  economic  construction 
requires  that  the  brace  C  shall  intersect  the  jib  A  at  a  distance 
from  the  mast  equal  to  four-fifths  of  the  extreme  effective  radius 
of  the  crane,  that  is,  that  the  distance  X  in  the  cut  should  be 
one-fourth  as  great  as  the  distance  Y.  When  for  any  reason  it 
is  necessary  that  the  brace  intersect  the  jib  at  a  point  nearer  to 
the  mast,  as,  for  instance,  at  C',  as  shown  by  the  dotted  lines  in 
cut,  a  much  greater  depth  is  necessary  in  the  irons  forming  the 
jib,  and  frequently  also  in  those  composing  the  mast.  It  is 
customary,  therefore,  to  proportion  the  several  parts  as  shown 


82 


A  Treatise  on  Cranes. 


in  the  cut,  unless  otherwise  ordered.  Where  it  is  possible  to 
obtain  greater  height  of  mast  above  the  jib,  as  indicated  by 
dotted  lines  at  M,  a  suspension-rod  N  may  be  substituted  for  the 


brace  C,  and  the  latter  omitted,  thus  giving  entire  freedom  below 
the  jib.  The  intersections  of  the  several  members  of  jib  cranes 
thus  constructed  are  best  united  by  the  overlapping  of  the  web 


Crane  Details. — Frames  and  Girders.         83 

of  one   part   upon  the  other,  and  by   gusset-plates,    all   firmly 
fastened  by  proper  riveting. 

Fig.  34  represents  the  transverse  section  of  the  bridge  of  a 
traveling  crane  of  medium  size,  which  consists  of  two  I-beams 
placed  side  by  side,  with  separators  between,  and  firmly  bolted 
together.     The   trolley-rails  are   placed  on  top  of   the  beams, 
and  the  construction  is  such  that  the  chains  from 
the  trolley  pass  outside  of  the  bridge.     Where  the 
load  to  be  carried  is  too  great,  or  the  span  too  wide 
to  permit  of  the  use  of  rolled  beams,  plate  girders, 
built  as  shown  in  Fig.  35,  are  used. 

This  girder  consists  of  a  thin  plate  of  wrought 
iron,  with  heavy  flanges  at  its  top  and  bottom  edges,  each  com- 
posed of  a  pair  of  angle  irons  riveted  through  the  plate  and  to  each 
other.  Each  of  the  angle  irons  forming  the  top  and  bottom  flanges 
of  such  girders  is  continuous,  and  rolled  in  a  single  piece.  At 
proper  intervals  vertical  struts,  formed  of  angle  iron, 
are  interposed  between  the  top  and  bottom  flanges  to 
reinforce  the  web  of  the  girder,  and  a  proper  rail  is 
placed  on  top  for  the  trolley  to  run  upon.  The  bridge 
is  formed  by  two  of  these  girders,  placed  side  by  side, 
and  in  large  cranes  the  hoisting  chains  pass  downward 
from  the  trolley  between  the  girders,  which  latter  are 
separated  sufficiently  to  enable  the  running  block  to 
rise  between  them. 

In  proportioning  the  frames  and  girders  of  the 
FIG.  35.  Weston  Cranes,  such  dimensions  are  adopted  as  will 
insure  a  factor  of  safety  of  six  throughout,  that  is,  such  that  the 
strains  developed,  with  the  maximum  load  suspended  at  the  center, 
or  point  of  greatest  strain,  shall  not  exceed  one-sixth  of  the  break- 
ing strength  of  the  material  employed.  We  state  the  case  in  this 
way  for  the  reason  that  it  is  still  customary  with  most  engineers 
to  make  such  calculations  upon  the  basis  of  an  assumed  "  factor 
of  safety."  The  best  and  latest  practice,  however,  is  to 
proportion  the  parts  with  reference  to  the  elastic  strength  of  the 
material  employed,  and  it  is  the  present  practice,  so  far  as 
possible,  to  give  such  dimensions  to  the  frames  and  girders  of 


84  A   Treatise  on  Cranes. 

the  Weston  Cranes,  that  under  no  condition  shall  any  of  their 
members  be  strained  to  within  50  per  cent,  of  the  elastic  limit  of 
the  material.  At  all  intersections  of  members,  and  at  points  of 
attachment  with  wrought  or  cast  iron  parts,  an  excess  of  strength 
is  always  provided  to  allow  for  the  weakening  of  bolt  and  rivet 
holes  and  other  contingencies.  Special  attention  is  given  to 
securing  unusual  strength  and  safety  in  these  details  of  the 
Weston  Cranes,  all  of  which  are  based  upon  exact  and  careful 
calculation.  A  comparison  of  one  of  these  cranes  with  most 
others  of  equal  nominal  capacity  will  show  much  difference  in 
the  amount  and  disposition  of  material  employed,  so  that, 
although  the  latter  may  possibly  lift  their  full  nominal  load 
without  breaking  down,  the  former  may  be  relied  upon  to  do  so 
always  with  absolute  safety.  Doubtless  a  load  of  10  tons  could 
be  lifted  with  a  5 -ton  Weston  Crane  without  disabling  it ;  but, 
in  executing  a  contract  to  furnish  a  Weston  Crane  of  10  tons 
capacity,  the  builders  furnish  one  proportioned  as  above  explained, 
and  of  a  strength  such  as  to  make  it  absolutely  safe  for  its 
intended  work. 


Crane  Details. — Bridges  and  Trestles.         85 


BRIDGES    AND    TRESTLES   OF    TRAVELING    CRANES. 

The  method  of  building  the  girders  composing  the  bridges 
of  traveling  cranes,  and  the  mode  of  constructing  their  trucks, 
have  been  already  described.  It  remains  to  describe  the  bridge 
as  a  whole  and  to  show  the  mode  of  supporting  it. 


FIG.  36. — Bridge  of  Hand  Traveling  Crane. 

Fig.  36  represents  a  plan,  with  end  and  side  elevations,  of 
the  bridge  of  a  hand  traveling  crane  composed  of  two  I-beams, 
as  shown  in  Fig.  34.  In  this  case  the  bridge  B  is  carried  at  each 
end  by  the  trucks  CC  traveling  upon  a  suitable  iron  or  steel  rail 
placed  on  the  trestles  AA.  Ordinarily  the  longitudinal  tracks 
are  supported  on  wooden  trestles  as  shown  in  the  cut,  but  they 
may  also  rest  on  wooden  stringers  placed  upon  a  brick  wall,  or 
be  carried  by  brackets  projecting  from  the  latter. 

Fig.  37  is  a  plan  of  the  bridge  of  a  large  power  traveling 
crane,  with  end  and  side  elevations  of  the  same.  BB  are  two 
girders,  each  built  as  shown  in  section  by  Fig.  35,  and  CC  are  the 
end-trucks  carrying  the  bridge,  the  construction  of  which  is 
shown  by  Fig.  32.  The  longitudinal  rails  rest  directly  upon 
wooden  stringers,  which  in  turn  are  supported  by  suitable  posts 
and  braces. 


86 


A   Treatise  on  Cranes. 


Ihe  construction  of  trestles  shown  in  Figs.  36  and  37  is  the 

one  ordinarily  resorted  to. 
In  some  cases,  however, 
wrought  iron  girders  are 
provided  for  supporting 
the  longitudinal  tracks, 
and  in  others  the  string- 
ers on  which  the  tracks 
rest  are  carried  directly 
upon  a  brick  wall,  or 
upon  suitable  brackets 
projecting  therefrom.  In 
all  cases  it  is  important 
that  such  stiffness  be  given 
to  the  stringers  support- 
ing the  longitudinal  tracks 
that  there  shall  not  be 
excessive  deflection  when 
5  the  load  passes  over  them. 

l|  J  [III  *|;M-  *      In  determining  their  di- 

mensions it  should  be 
remembered  that  each 
trestle  carries  one-half  of 
the  weight  of  the  crane, 
and  is  liable  to  carry 
almost  the  whole  of  the 
live  load.  Thus,  if  the 
weight  of  the  crane  itself 
be  6  tons,  and  the  maxi- 
mum load  to  be  carried 
be  10  tons,  when  the  load 
is  at  the  center  of  the 
bridge  the  truck  at  either 
end  will  receive  a  total 
load  of  8  tons,  and  the 
trestle  supporting  the 
track  on  which  the  truck 


Crane  Details. — Bridges  and  Trestles.         87 

is  to  run  should  be  proportioned  to  safely  carry  the  whole  load 
distributed  upon  the  two  wheels  of  the  truck,  the  load  on  each 
of  the  latter  in  the  above  case  being  4  tons.  As,  however,  the 
maximum  load  may  be  suspended  from  one  end  of  the  bridge, 
either  truck  is  liable  to  receive  the  whole  of  the  load  (nearly),  say, 
in  the  above  case,  10  tons,  in  addition  to  one-half  the  weight  of 
the  bridge,  say  3  tons,  making  in  all  13  tons,  or  6%  tons  on 
each  wheel,  and  this  fact  should  be  kept  in  view  in  designing 
the  trestles  for  supporting  such  a  crane. 

Stiffness,  as  well  as  ultimate  strength,  is  important  in  the 
trestles  for  the  longitudinal  tracks,  since  deflection  of  the  tracks 
between  supports  would  give  an  undulating  line,  so  that  the 
crane  would  at  one  time  be  upon  a  down-grade  and  at  others  be 
compelled  to  climb  an  up-grade.  The  latter  would  of  course 
greatly  increase  the  traction  of  the  crane  and  cause  unnecessary 
strain  upon  all  of  the  driving  gear. 

One  of  the  chief  merits  of  traveling  cranes  as  compared  with 
jib  cranes  is  that  they  entirely  avoid  the  severe  lateral  strains 
upon  the  walls  and  roof  of  the  building  which  exist  where  heavy 
jib  cranes  are  employed.  The  entire  weight  of  a  traveling  crane 
and  its  load  rests  directly  upon  the  longitudinal  tracks  and  their 
supports,  so  that  vertical  strains  only  have  to  be  considered. 
These  are  usually  and  preferably  resisted  by  suitable  posts 
extending  to  the  ground,  so  that  the  walls  or  frame  of  the 
building  are  unaffected  by  the  loads  upon  the  crane,  and  need 
have  only  the  dimensions  required  for  the  proper  construction 
and  support  of  the  building  itself. 


88  A    Treatise  on  Cranes. 


POWER    TRANSMISSION. 

For  the  transmission  of  power  from  a  fixed  motor  to  a 
traveling  or  other  movable  crane,  either  cotton  or  wire  rope  may 
be  employed,  according  to  the  conditions  of  the  case. 

Where  wire  rope  is  employed,  rubber-lined  driving  and 
guide  wheels,  of  large  diameter,  and  having  deep  flanges  to  insure 
the  proper  delivery  of  the  rope  to  the  wheel,  are  required. 

Fig.  38  is  a  cross-section  of  the  rim  of  a  wheel  for  wire 
rope,  showing  the  rubber  lining  contained  in  a  dove-tailed  recess 
at  the  bottom  of  the  groove.     The  diameter  of 
driving  wheels  of  this  kind  should  be  at  least  4 
feet,  and  of  the  guiding  wheels  not  less  than  3 
feet.     Fig.  39  represents  the  rim  of  a  wheel  for 
cotton    rope,   the    groove    in    which   is   simply 
turned  and  polished,  the  diameter  of  the  wheel 
FIG.  38.     5eing  about  three  feet. 

Wire  ropes,  where  employed,  are  used  with  velocities  varying 
from  1,000  to  2,000  feet  per  minute,  according  to  requirements  ; 
cotton  rope  usually  at  a  velocity  of  about  5,000  feet  per  minute. 
Both  kinds  of  rope  have  their  advantages  under  certain 
conditions,  but  it  is  preferable  in  most  cases  to  use  cotton  rope  at 
high  velocity.  In  England  this  has  been  done  for  many  years, 
but  usually  under  a  system  of  construction  by  which  the  power 
is  taken  from  the  rope  by  pressing  small  sheaves  against  it  while 
in  motion,  and  thus  imparting  a  greater  or  less  velocity  to  the 
wheels  in  proportion  to  the  pressure  with  which  they  are  forced 
against  the  rope.  As  employed  in  the  Weston  Cranes,  on  the 
contrary,  the  rope  is  usually  in  permanent  contact  with  the  driving 
wheel,  so  that  the  latter  moves  constantly  with  a  circumferential 
velocity  equal  to  that  of  the  rope,  and  the  power  thus  transmitted 
is  utilized  in  the  mechanism  in  the  various  modes  explained 
under  the  heads  of  the  several  types  of  cranes.  Thus  used,  the 


Crane  Details. — Power   Transmission.          89 

cotton  rope  is  much  more  durable  and  reliable  than  when 
employed  as  in  the  English  cranes  referred  to ;  and  experience 
justifies  the  statement  that,  under  most  conditions,  a  cotton  rope 
thus  used  is  in  every  way  better,  more  durable,  and  more  satis- 
factory than  wire  rope  for  the  transmission  of  power  to  cranes. 


FIG.  40. — Transmission  of  Power. 


Fig.  40  represents  the  usual  method  of  transmitting  power  to 
a  Weston  traveling  crane.  Referring  to  the  cut,  it  will  be  seen 
that  there  are  three  rope  wheels  attached  to  the  end  of  the  bridge, 
the  two  outer  ones  being  guide  wheels,  over  which  the  rope  is 
deflected  to  the  driving  wheel  in  the  center,  the  shaft  of  which 
latter  communicates  motion  to  the  mechanism  on  the  bridge.  At 
the  left  hand  is  the  rope-driving  wheel,  and  at  the  opposite  end 
an  idler  over  which  the  rope  returns  and  passes  to  the  crane. 
This  idler  is  mounted  in  a  frame  moving  between  guides,  and 
strained  by  a  suitable  weight  so  as  to  give  the  requisite  amount 
of  tension  on  the  driving  rope,  and  to  automatically  compensate 
for  the  stretch  of  the  rope.  The  same  arrangement  suffices  both 
for  wire  and  cotton  ropes,  and  with  slight  modifications  is 
employed  also  for  the  transmission  of  power  to  walking,  jib,  and 
other  power  cranes. 

Where  possible,  it  is  always  best  that  the  slack  side  of  the 
driving  rope  should  be  below  ;  and  where  its  length  is  great  it 
may  be  supported  at  intervals  upon  suitable  guide  sheaves  so  as 
to  prevent  undue  deflection. 


9o 


A   Treatise  on  Cranes. 


TAKE-UPS. 

In  connection  with  the  wire-rope  system  of  bridge  propulsion 
previously  described,  it  is  found  desirable  to  employ  some  means 
for  automatically  taking  up  the  slack  in  the  fixed  cables  resulting 
from  their  gradual  stretching. 

For  this  purpose  the  "take-up"  illus- 
trated in  Fig.  41,  is  employed,  consisting 
of  the  bracket  A  securely  attached  to  a 
wall  or  post  at  the  end  of  the  longitudinal 
tracks,  and  carrying  at  its  outer  end  a 
short  shaft,  attached  to  one  end  of  which 
is  the  small  sheave  C,  and  to  the  other 
end  the  larger  sheave  B.  On  one  side 
of  the  latter  is  formed  the  ratchet  wheel 
,  and  engaging  with  this  is  the  pawl  G, 
pivoted  to  the  bracket  A.  E  is  the  fixed 
cable  for  squaring  and  propelling  the 
bridge  of  the  crane,  and  F  is  a  similar 
rope  wound  upon  the  sheave  B,  and  having  suspended  from  it  a 
suitable  weight. 

Whenever  the  fixed  cable  E  has  stretched  appreciably  in 
service,  the  slack  resulting  therefrom  is  taken  up  by  the  action 
of  the  weight  suspended  from  the  rope  F,  which,  acting  through 
the  sheave  B  and  its  shaft,  causes  the  sheave  C  to  revolve,  thus 
winding  upon  the  latter  a  portion  of  the  fixed  cable  E.  This  ac- 
tion will  take  place  in  each  pair  of  take-ups  at  a  time  when  the 
bridge  is  moving  away  from  them,  and  when,  consequently,  the 
portion  of  the  cable  between  them  and  the  bridge  is  relaxed.  It 
will  occur  automatically  whenever  there  is  sufficient  slack  to  per- 
mit the  ratchet  wheel  D  to  be  moved  one  tooth  forward.  In  this 
way  the  fixed  cables  are  maintained  permanently  at  a  proper  ten- 
sion to  effectively  perform  their  work. 


FIG.  41.— Take-up. 


Crane  Details. — Hooks.  91 


HOOKS. 

A  small  but  important  element  of  the  suspending  apparatus 
of  a  crane  is  the  hook  which  terminates  it,  and  by  which  the  hoist- 
ing mechanism  is  attached  to  or  connected  with  the  load  to  be 
lifted. 

In  1875  all  of  the  various  patents  relating  to  the  Weston 
Differential  Pulley  Block  passed  into  their  present  ownership, 
and  in  organizing  for  the  manufacture  of  the  blocks,  it  was 
found  that  previous  practice  in  the  construction  of  the  hooks 
had  been  very  loose  and  variable.  To  determine  the  correct  pro- 
portions of  hooks  the  author  undertook  a  careful  study  of  the  sub- 
ject, which  led  ultimately  to  long  investigation  and  numerous  exper- 
imental tests  for  the  purpose  of  determining  the  best  shapes  and 
dimensions  of  the  several  parts  of  the  hook,  in  order  to  obtain  ap- 
proximately uniform  strength  throughout,  and  to  utilize  the  iron, 
of  which  the  hook  was  formed,  in  the  most  advantageous  and 
economical  manner. 

The  investigation  thus  commenced  showed  that  the  strains 
developed  in  hooks  are  of  an  exceedingly  complex  character,  and 
the  determination  of  the  correct  proportions  of  the  several  parts 
was  only  reached,  after  much  study  and  discussion,  by  means  of 
mathematical  calculations  of  much  intricacy  and  based  upon  the 
results  of  numerous  experiments.  The  investigation  was  com- 
menced and  conducted  by  the  writer,  assisted  by  the  late  Mr. 
Robert  Briggs,  C.  E.,  and  by  Mr.  T.  W.  Capen,  in  addition  to 
which  assistance  in  the  mathematical  inquiry  was  obtained  from 
Professor  Lanza,  of  the  Massachusetts  Institute  of  Technology. 
The  experimental  tests  were  partly  conducted  by  Professor  Thur- 
ston,  at  the  Stevens  Institute  of  Technology,  Hoboken,  N.  J.,  and 
partly  in  the  works  of  The  Yale  &  Towne  Manufacturing  Co. 
These  facts  are  mentioned  to  indicate  the  exhaustive  manner  in 
which  the  inquiry  was  conducted.  It  is  believed  that  the  investi- 
gation of  the  subject  was  more  thorough  than  any  other  that  has  ever 
been  made,  and  that  the  results  are  proportionately  reliable. 


92  A    Treatise  on  Cranes. 

Without  undertaking  here  to  narrate  the  intermediate  steps 
of  the  investigation,  we  will  simply  give  the  final  results  in  the 
form  of  the  working  formulae. 


FIG.  42. — Standard  Hook. 

Fig.  42  represents,  to  a  scale  of  one-sixth  natural  size,  a  5 -ton 
hook  of  the  dimensions  and  shape  determined  by  the  following 
formulae,  which  give  the  dimensions  of  the  several  parts  of  hooks 
of  capacities  from  250  pounds  (or  one-eighth  of  a  ton)  up  to 
20,000  pounds  (or  10  tons).  For  hooks  of  larger  sizes  the  formu- 
lae become  slightly  different,  the  general  proportions,  however, 
remaining  the  same. 

For  economy  of  manufacture  each  size  of  hook  is  made  from 
some  regular  commercial  size  of  round  iron.  The  basis,  or  initial 
point,  in  each  case  is,  therefore,  the  size  of  iron  of  which  the  hook 
is  to  be  made,  which  is  indicated  by  the  dimension  A  in  the  dia- 
gram. The  dimension  D  is  arbitrarily  assumed.  The  other  di- 
mensions, as  given  by  the  formulae,  are  those  which,  while  preserv- 
ing a  proper  bearing-face  on  the  interior  of  the  hook  for  the  ropes 
or  chains  which  may  be  passed  through  it,  give  the  greatest  re- 
sistance to  spreading  and  to  ultimate  rupture,  which  the  amount 
of  material  in  the  original  bar  admits  of.  The  symbol  A  is  used 


Crane  Details.  —  Hooks.  93 

in  the  formulae  to  indicate  the  nominal  capacity  of  the  hook  in  tons 
of  2,000  pounds.  The  formulae  which  determine  the  lines  of  the 
other  parts  of  the  hooks  of  the  several  sizes  are  as  follows,  the 
measurements  being  all  expressed  in  inches  :  — 

D=.5    A  +1.25  G=-75  D 

E  =  .64A+i.6o  0=1.363  A  4    .66 

.85  Q=.64   A+i.6o 


H  —  i.oSA  L=i.o5A 


J  =i.2oA  N=  .85B-.16 

U=  .866A 


EXAMPLE.  —  To  find  the  dimension  D  for  a  2-ton  hook.  The 
formula  is:  — 

D=.5  A+i.25 

and  as  A  =2  the  dimension  D  by  the  formula  is  found  to  be  2% 
inches. 

The  dimensions  A  are  necessarily  based  upon  the  ordinary 
merchant  sizes  of  round  iron.  The  sizes  which  it  has  been  found 
best  to  select  are  the  following:  — 

Capacity  of  Hook  i,   i,  £,    i,     i£,   2,    3,    4,    5,    6,    8,     10     tons. 
Dimension  A.  .  .  -£,  -fj-,  f,  i-^-,  ij,  if,  if,  2,  2-J-,  2$,  2$,  3!  inches. 

The  formulae  which  give  the  sections  of  the  hook  at  the  sev- 
eral points  are  all  expressed  in  terms  of  A  and  can  therefore  be 
readily  ascertained  by  reference  to  the  foregoing  scale. 

EXAMPLE.  —  To  find  the  dimension  I  in  a  2-ton  hook.  The 
formula  is  I  =  1.33  A,  and  for  a  2-ton  hook  A  =  if  inch.  Therefore 
I,  in  a  2-ton  hook,  is  found  to  be  i-^f-  inch. 

Experiment  has  shown  that  hooks  made  according  to  the 
above  formulae  will  give  way  first  by  opening  of  the  jaw,  which, 
however,  will  not  occur  except  with  a  load  much  in  excess  of 
the  nominal  capacity  of  the  hook.  This  yielding  of  the  hook 
when  overloaded  becomes  a  source  of  safety,  as  it  constitutes  a 
signal  of  danger  which  cannot  easily  be  overlooked,  and  which 
must  proceed  to  a  considerable  length  before  rupture  will  occur 
and  the  load  be  dropped.  A  comparison  of  these  hooks  with 
most  of  those  in  ordinary  use  will  show  that  the  latter  are,  as  a 
rule,  badly  proportioned,  and  frequently  dangerously  weak. 


94 


A    Treatise  on  Cranes. 


BLOCKS    AND    BUSHINGS. 


In  the  smaller  sizes  of  Weston  Cranes  the  same  form  of  blocks 
is  used  as  in  the  Weston  Differential  Pulley  Blocks,  as  illustrated 
in  Part  IV. 


FIG.  43.— Crane  Block  and  Hook. 

In  the  larger  sizes  the  construction  of  block  employed  is  that 
illustrated  in  Fig.  43,  in  which  AA  are  the  chain  sheaves,   BB 


Crane  Details. — Blocks  and  Bushings.         95 

the  wrought  iron  sides  or  cheek  plates,  C  the  pin,  D  the  cross- 
head,  and  E  the  hook.  The  sheaves  AA  are  properly  grooved 
to  receive  the  chain.  The  cross-head  D  is  pivoted  in  the  plates 
BB,  and  the  hook  E  turns  freely  within  it,  so  that  a  compound 
motion  is  obtained  which  permits  the  hook  to  be  turned  in  any 
desired  position.  Heavy  cast  iron  sides  are  sometimes  bolted  to 
the  cheek  plates  to  give  additional  weight  to  the  block  to  assist 
in  overhauling  the  chains  when  no  other  load  is  on  them. 


FIG.  44. — Anti-friction  Bushing. 

Fig.  44  represents  one  of  the  sheaves  A  removed  from  the 
block,  and  shows  the  construction  of  anti-friction  roller  bushing 
which  is  employed  in  all  of  the  larger  Weston  Cranes  to  diminish 
the  friction  of  the  sheaves,  both  in  the  running  block  and  in  the 
trolley.  Referring  to  the  cut,  C  is  the  pin  upon  which  the  sheave 
A  revolves,  and  GGG  are  a  series  of  steel  rollers  lying  between 
the  pin  and  the  sheave.  H  is  a  brass  cage,  composed  of  an  an- 
nular rim  at  each  end,  with  radial  bars  uniting  the  two  rims  and 
acting  as  separators  between  each  pair  of  the  steel  rollers.  Each 
roller  is  thus  separated  from  its  two  neighbors  by  two  of  these 
bars,  and  is  confined  endwise  between  the  two  annular  rims  of  the 
cage  H.  The  entire  cage  revolves  with  the  rollers,  but  at  a 
speed  equal  to  the  circumferential  velocity  of  the  rollers,  and 
therefore  much  slower  than  that  of  the  sheave  A. 


96  A    Treatise  on  Cranes. 

Long  experience  has  demonstrated  that  this  form  of  anti- 
friction bushing,  while  very  simple,  is  exceedingly  durable  and 
efficient.  It  requires  little  care  or  attention,  and  performs 
satisfactorily  under  the  most  trying  conditions. 

These  bushings  are  also  used  in  the  wheels  of  trolleys  where 
the  limitations  of  head-room  require  the  latter  to  be  of  small  di- 
ameter. 


Crane  Details. — Pillar  Crane  Foundations.      97 


PILLAR    CRANE    FOUNDATIONS. 


FIG.  45. —  Pillar  Crane  and  Foundation. 

Fig.  45  is  a  half  sectional  view  of  a  Pillar  Crane,  showing  the 
construction  of  its  foundation. 

In  this  case  the  crane  is  entirely  supported  from  below,  and 
the  masonry  which  forms  the  foundation  must  have  sufficient 
stability  to  resist  the  overturning  tendency  caused  by  the  load 
hanging  from  the  outer  end  of  the  boom.  Where  the  surrounding 
ground  is  sufficiently  firm  the  proportions  of  this  foundation  are 
about  as  represented  in  the  figure.  On  filled  ground,  piling  or 
a  timber  platform  beneath  the  masonry,  or  both,  may  be  necessary. 
These  questions  can  only  be  properly  determined  by  a  considera- 
tion of  the  fact  in  each  case. 


98  A    Treatise  on  Cranes. 

Referring  to  the  cut,  A  is  the  column  of  Crane,  and  B  the 
boom  carrying  the  upper  block  and  revolving  around  the  fixed 
mast  or  column  A.  D  is  the  masonry  foundation,  E  a  heavy  iron 
plate  or  ring  embedded  in  the  masonry  near  its  bottom,  FF 
foundation  bolts  passing  through  this  ring  and  through  the  base 
of  the  pillar  A,  thus  securely  fastening  the  latter  to  the  founda- 
tion. The  foundation  D  may  consist  of  ordinary  rubble 
masonry,  covered  with  a  cap  stone  C,  the  upper  surface  of  which 
should  be  dressed  smooth  to  receive  the  base  of  the  pillar  A. 
After  the  completion  of  the  foundation  the  ground  surrounding 
it  should  be  refilled  and  thoroughly  packed  by  ramming  or 
puddling,  so  as  to  assist  the  foundation  in  resisting  the  strains 
caused  by  the  crane. 


Crane  Details. — Patents.  99 


NOTICE 

AS    TO    RIGHTS   SECURED    BY    PATENT. 

The  numerous  inventions  and  improvements  embodied  in 
the  various  cranes  illustrated  and  described  in  this  book  have 
been  patented  from  time  to  time  as  they  have  been  invented,  so 
that  all  of  the  important  mechanism  of  the  cranes,  both  in  its 
general  features  and  in  detail,  is  covered  by  patents  belonging  to 
The  Yale  &  Towne  Manufacturing  Co.,  which,  therefore,  has  the 
sole  right  to  make  and  sell  cranes  embodying  these  patented 
features. 

A  list  of  the  Company's  patents  already  issued  relating  to 
cranes  is  given  on  page  103,  to  which  attention  is  particularly 
called,  but  for  convenience  we  give  below,  in  a  condensed  form, 
the  substance  of  some  of  the  points  which  are  claimed  in  these 
patents  and  covered  thereby.  This  condensation  is  given  merely 
for  the  convenience  of  readers  and  without  prejudice  in  any  man- 
ner to  any  rights  of  the  company. 

CLAIMS  OF  PATENTS — CONDENSED. 

First — The  system  of  propelling  the  bridge  of  a  crane  by 
means  of  a  cable  or  cables  whereby  the  crane  is  pulled  in  either 
direction  desired. 

Second — The  use  of  fixed  or  movable  cables  in  connection 
with  the  bridge  of  a  traveling  crane,  whereby  the  bridge,  when 
moved,  is  compelled  by  the  cables  to  travel  in  a  direction  parallel 
to  its  longitudinal  tracks. 

Third — The  combination  in  a  crane  of  cables,  grip  wheels, 
and  a  driving  shaft  provided  with  suitable  driving  and  reversing 
mechanism,  so  that  the  grip  wheels  may  be  rotated  to  drive  the 
crane  in  either  direction  as  desired. 

Fourth — The  use,  in  a  crane,  of  two  grip  wheels  rigidly  con- 


ioo  A  Treatise  on  Cranes. 

nected  with  a  common  shaft,  and  two  independent  cables,  one  of 
which  cables  is  led  into  engagement  with  its  grip  wheel  in  a  direc- 
tion contrary  to  that  of  the  other,  so  that  while  both  the  wheels 
are  rotated  in  one  direction,  the  cables  will  be  strained  or  pulled 
from  contrary  directions,  thus  causing  the  bridge  to  travel  either 
Way  as  desired. 

Fifth — An  endless  hoisting  chain  operated  by  or  used  in  con- 
nection with  two  independent  chain  wheels  or  drums. 

Sixth — An  endless  hoisting  chain  in  connection  with  two  in- 
dependent chain  wheels  and  intermediate  gearing,  whereby  one 
side  of  the  chain  may  be  paid  out  and  the  other  pulled  in  simul- 
taneously and  at  equal  speeds,  in  order  to  cause  traverse  of  the 
trolley. 

Seventh — Constructing  the  hoisting  gear  of  a  crane  in  such 
manner  that  the  movement  of  the  trolley  in  either  direction  is 
effected  by  the  same  mechanism  as  employed  to  effect  hoisting 
and  lowering,  thus  dispensing  with  the  necessity  of  additional 
gearing  for  this  purpose. 

Eighth — The  combination  in  the  mechanism  of  a  power  crane 
of  a  continuously  rotating  shaft  and  two  other  independent  shafts, 
either  one  or  both  of  which  can  be  caused,  simultaneously  or  in- 
dependently, to  rotate  in  the  same  direction  with,  or  in  a  direction 
opposite  to,  the  continuously  rotating  shaft,  so  that,  while  the 
driving  wheel  of  the  crane  rotates  continuously  in  one  direction, 
power  may  be  taken  off  from  it  for  hoisting  or  lowering,  and  for 
traversing  the  crane  on  its  tracks  or  the  trolley  on  the  bridge,  as 
desired. 

Ninth — The  combination,  with  any  appropriate  friction  clutch, 
of  a  toggle  joint  lever  or  levers,  and  a  sliding  collar  for  actuating 
the  toggle  joint,  the  construction  being  such  that  the  end  thrust 
of  the  clutch  is  absorbed  within  the  shaft  itself,  and  all  collar  fric- 
tion thereby  avoided. 

Tenth — In  a  traveling  crane  the  location  of  the  operating 
mechanism  at  one  end  of  and  beneath  the  bridge,  the  several 
chains  and  ropes  being  suitably  guided  thereto  from  above,  so 
that  the  bridge  may  be  placed  as  close  as  possible  to  the  roof  or 
ceiling  and  head-room  thereby  economized. 


Crane  Details. — Patents.  101 

Eleventh — A  crane  trolley  with  a  central  aperture  through 
which  passes  the  bridge  or  girder  on  which  the  trolley  travels, 
so  that  the  trolley  and  its  attached  mechanism  entirely  surround 
the  girder,  thus  economizing  head-room. 

Twelfth — A  crane  trolley  provided  with  a  brake  arranged  to 
be  actuated  from  any  convenient  fixed  point  on  the  crane,  whereby 
the  operator  can  lock  the  trolley  in  any  desired  position  and  so 
prevent  its  "creeping"  on  its  tracks  during  hoisting  and  lowering. 

Thirteenth — A  brake  for  preventing  motion  of  a  trolley  so 
constructed  as  to  be  automatically  released  whenever  the  trolley- 
moving  mechanism  is  in  action,  but  at  all  times  when  hoisting  or 
lowering  occurs  to  automatically  hold  the  trolley  stationary,  so 
that  it  cannot  "  creep  "  on  its  tracks. 

Fourteenth — A  sustaining  brake,  to  prevent  running  down 
of  the  load,  so  connected  with  the  operating  levers  of  a  power 
crane  that  the  brake  is  automatically  released  whenever  the  levers 
are  moved  to  cause  hoisting  or  lowering,  but  is  self-applied  at  all 
other  times. 

Fifteenth — An  automatic  stop  to  prevent  over-travel  of  the 
bridge  of  a  traveling  crane  at  either  end  of  its  longitudinal  tracks. 

Sixteenth — An  automatic  stop  to  prevent  over-travel  of  the 
trolley  at  either  end  of  the  bridge  or  jib  of  a  crane. 

Seventeenth — The  use  in  a  crane  of  two  hand-rope  wheels,  of 
differential  diameters,  engaging  directly  or  indirectly  with  two 
parts  of  the  same  hoisting  chain,  whereby  a  variety  of  speeds  is 
obtained.  ( 

Eighteenth — An  automatic  "take-up"  constituting  a  rigid 
fastening  for  the  end  of  a  fixed  cord  or  cable  when  the  latter  is 
under  strain,  but  capable,  when  the  strain  is  relaxed,  of  automatic- 
ally taking  up  the  slack  arising  from  stretching. 

Nineteenth — A  truck  for  the  bridge  of  a  crane  consisting  of 
two  wheel-brackets,  one  on  each  side  of  the  girder  or  bridge,  and 
a  bolt  so  placed  as  to  properly  resist  the  tensional  strain  and  to 
securely  hold  all  of  the  several  parts  together. 

Twentieth — A  trolley  arranged  to  travel  on  the  inclined  bot- 
tom flanges  of  a  beam  and  having  inclined  wheel  bearings,  whereby 
the  axis  of  each  wheel  is  parallel  with  the  face  or  bearing  of  its 


1O2  A  Treatise  on   Cranes. 

track,  so  that  cylindrical  wheels,  which  have  a  perfect  rolling  con- 
tact, without  rubbing  or  sliding,  can  be  used  instead  of  conical 
wheels. 

Twenty-first — An  I-beam,  or  other  flanged  tram-rail,  provided 
with  a  pocket  in  the  upper  part  of  its  web,  and  a  bolt  and  nut, 
supporting  the  beam  from  above,  contained  within  the  pocket 
and  not  interfering  with  the  wheels  of  the  trolley,  so  that  the  latter 
may  be  as  large  as  the  beam  admits  of. 

Twenty-second — A  switch  on  a  suspended  tram-rail,  one  end 
of  which  is  supported  by  a  pivot  and  the  other  by  a  yoke  or  head 
resting  upon  any  number  of  tracks  which  it  is  desired  to  connect 
with  the  switch. 


List  of  Patents. 


103 


LIST    OF    PATENTS 

[ISSUED  BY  THE  UNITED  STATES] 

RELATING    TO 

DEVICES  ILLUSTRATED  AND  DESCRIBED  IN  THIS  BOOK. 


No.     67,470  (Reissue),  -  July  9,  1872. 

No.  212,339,     - 

February  18,  1879. 

No.     75,227, 

-     -       March  3,  1868. 

No.  216,298, 

-     -  June  10,  1879. 

No.    98,000, 

-     December  14,  1869. 

No.  217,030,     - 

July  I,  1879- 

No.  119,981, 

-     -  October  17,  1871. 

No.  217,031,     - 

-    -     July  i,  1879. 

No.  123,342, 

-     -  February  6,  1872. 

No.  217,032,     - 

-    -     July  I,  1879. 

No.  126,391, 

-      May  7,  1872. 

No.  229,092,     - 

-     -  June  22,  1880. 

No.  127,689, 

-     -     -  June  n,  1872. 

No.  237,675,     - 

February  15,  1881. 

No.  129,914, 

-    -    -   July  30,  1872. 

No.  239,408,     - 

-     March  29,  1881. 

No.  134,337, 

-     December  24,  1872. 

No.  241,764,     - 

-     -    May  17,  1881. 

No.  134,957, 

-     -  January  14,  1873. 

No.  242,271,     - 

-     -    May  31,  1881. 

No.  134,958, 

-     -  January  14,  1873. 

No.  255,827,     - 

-     -    April  4,  1882. 

No.  155,210, 

-   September  22,  1874. 

No.  263,479,     - 

-    August  29,  1882. 

No.  155,779, 

-     -     October  6,  1874. 

No.  267,149,     - 

November  7,  1882. 

No.  157,660, 

December  8,  1874. 

No.  270,279,     - 

-     January  9,  1883. 

No.  157,661, 

December  8,  1874. 

No.  270,386,     - 

-     January  9,  1883. 

No.  157,662, 

December  8,  1874. 

No.  271,311,     - 

-  January  30,  1883. 

No.  185,060, 

December  5,  1876. 

No.  272,608,     - 

February  10,  1883. 

No.  187,745, 

February  27,  1877. 

No.  273,462, 

-     -  March  6,  1883. 

No.  194,019, 

-     -      August  7,  1877. 

No.  275,465, 

-  April  10,  1883. 

No.  198,718, 

-     December  25,  1877. 

No.  278,774, 

-     -     June  5,  1883. 

No.  212,337, 

-      February  18,  1879. 

No.  278,775,     - 

-     -     June  5,  1883. 

No.  212,338, 

-      February  18,  1879. 

No.  279,704,     - 

-     -  June  19,  1883. 

No.  279,705.     -     .     -   June  19,  1883. 

PART   III. 


PART   III. 


INTRODUCTION. 


In  this  part  is  comprised  a  series  of  illustrations  of  completed 
cranes,  of  numerous  types,  together  with  sufficient  descriptive 
matter  in  each  case  to  indicate  clearly  the  general  construction 
and  operation  of  the  crane,  and  the  uses  to  which  it  is  applicable. 
All  descriptions  of  details,  however,  are  omitted,  except  suitable 
references  to  the  pages  in  Part  II,  where  they  are  fully  illustrated 
and  described. 

In  preparing  the  following  illustrations  of  cranes  it  was  a 
question  whether  to  represent  merely  the  machines  themselves, 
without  surroundings,  or  to  include  also  the  accessories  by  which 
each  of  the  several  types  of  cranes  is  ordinarily  surrounded.  The 
former  would  have  involved  only  the  reproduction  of  working 
drawings ;  the  latter  required  the  preparation  of  a  series  of 
pictures.  The  plan  of  pictorial  representation  was  adopted  as 
tending  to  best  present  the  subject  to  the  general  reader,  and  as 
more  suggestive  of  the  applications  and  uses  of  the  various  types 
of  cranes.  The  illustration  in  each  case  represents  merely  one 
of  the  many  uses  to  which  the  several  types  of  cranes  are  appli- 
cable. Most  of  them  are  drawn  from  cranes  already  in  use,  and 
with  the  actual  surroundings.  The  effort  has  been  rather  to 
represent  intelligently  the  appearance  of  the  crane  in  actual  use 
than  to  accurately  indicate  the  several  details  of  its  construction. 
The  illustrations  contained  in  this  Part  will,  it  is  hoped,  conduce 
to  a  better  realization  of  the  wide  range  of  uses  to  which  cranes 
can  with  advantage  and  economy  be  applied. 


io8  A  Treatise  on  Cranes. 


FIG.  46. — Swing  Crane,  without  Trolley. 


Swing  Crane.  109 


SWING   CRANE. 

WITH    WINCH. 
SINGLE    IRON    FRAME. — WITHOUT    TROLLEY. 

Fig.  46  represents  the  simplest  form  of  rotary  crane,  in  which 
each  member  of  the  frame  consists  of  a  single  iron  beam,  and  in 
which  the  hoisting  chain  passes  over  a  fixed  sheave  at  outer  end 
of  jib,  so  that  the  only  motions  are  those  of  hoisting  and  lowering, 
and  of  rotation.  This  construction  is  applicable  to  cranes  of 
capacities  from  100  to  1,000  pounds.  For  larger  sizes  it  is  usually 
preferable  to  employ  a  trolley,  as  in  the  crane  shown  by  Fig.  49. 

Each  member  of  the  frame  of  this  crane  consists  of  a  single 
wrought  iron  I-beam,  suitably  connected  at  their  intersections. 
As  the  load  is  not  to  be  moved  inward  upon  the  jib  the  latter  is 
usually  supported  by  a  brace,  as  shown  ;  although,  where  desired, 
a  tension  rod  may  be  substituted  for  the  brace,  as  explained  on 
page  82,  in  which  case  the  appearance  of  the  frame  will  be 
substantially  like  that  of  the  crane  illustrated  by  Fig.  48. 

The  hoisting  gear  consists  of  a  pocketed  chain  wheel,  driven 
by  spur  gearing,  with  a  frictional  safety  ratchet  upon  the  primary 
shaft,  so  that  the  load  is  always  self-sustained  in  any  position 
and  cannot  run  down.  Lowering  is  easily  effected  by  reversing 
the  motion  of  the  crank,  but  ceases  automatically  whenever  this 
motion  is  discontinued. 

Rotation  is  effected  by  simply  pushing  or  pulling  the  sus- 
pended load,  and  the  construction  of  the  top  and  bottom  pintles 
upon  which  the  crane  revolves  is  such  as  to  reduce  friction  to  a 
minimum. 

This  crane  is  especially  adapted  to  light  work  in  smith  shops, 
boiler  shops,  etc.,  and  for  use  in  loading  and  unloading  merchan- 
dise in  stations,  wharves  and  warehouses. 

Estimates  will  be  furnished  on  receipt  of  information  stating 
maximum  load  to  be  lifted,  height  from  floor  to  ceiling,  and 
radius  of  jib. 


I  IO 


A   Treatise  on  Cranes. 


FIG.  47.— Light  Jib  Crane,  with  Trolley  and  Pulley  Block. 


Jib  Cranes.  in 


JIB    CRANE. 

FOR    DIFFERENTIAL    PULLEY    BLOCK. 
SINGLE     IRON     FRAME. WITH     TROLLEY. 

Fig.  47  represents  a  light  Jib  Crane  in  which  each  member 
of  the  frame  consists  of  a  single  iron  I-beam,  and  in  which  the 
hoisting  mechanism  consists  of  a  differential  pulley  block  sus- 
pended from  a  trolley  traveling  upon  the  bottom  flange  of  the 
jib.  This  construction  is  applicable  to  cranes  of  capacities  from 
500  pounds  to  2  tons.  For  larger  sizes  it  is  usually  preferable 
to  employ  the  construction  shown  by  Fig.  49. 

Each  member  of  the  frame  consists  of  a  single  wrought  iron 
I-beam,  suitably  connected  at  their  intersections.  As  a  brace 
under  the  jib  (as  shown  by  Fig.  46)  would  necessarily  restrict  the 
motion  of  the  trolley,  the  jib  is,  if  possible,  always  supported  by  a 
tension  rod  above,  so  that  the  trolley  is  free  to  move  inward 
close  to  the  mast.  No  gearing  of  any  kind  is  attached  to  the 
crane.  Hoisting  and  lowering  are  effected  by  a  Weston  Differential 
Pulley  Block  suspended  from  the  trolley,  by  means  of  which  the 
load  is  always  self-sustained  at  any  desired  height.  Motion  of 
the  trolley  is  effected  by  pulling  or  pushing  the  suspended  load, 
and  rotation  is  effected  in  like  manner. 

This  Crane  is  adapted  to  handling  light  work  in  machine 
shops,  forges,  boiler-shops,  etc.,  and  is  particularly  convenient 
for  erecting  light  machine  work,  or  for  setting  it  in  lathes  and 
planers. 

Estimates  will  be  furnished  on  receipt  of  information  stating 
maximum  load  to  be  lifted,  height  from  floor  to  ceiling,  and 
radius  of  jib. 


I  12 


A  Treatise  on  Cranes. 


FIG.  48.— Light  Jib  Crane,  with  Trolley. 


Jib  Cranes.  1 1 3 


JIB  CRANE. 

WITH    WINCH    AND    TRAVERSE    GEAR. 
SINGLE     IRON     FRAME. — WITH     TROLLEY. 

Fig.  48  represents  a  light  Jib  Crane,  similar  to  that  shown 
by  Fig.  47,  but  provided  with  mechanism  for  moving  the  trolley 
in  and  out  upon  the  jib,  and  other  mechanism  for  hoisting  and 
lowering  the  load,  all  permanently  attached  to  the  crane.  This 
mode  of  construction  is  applicable  to  cranes  of  capacities  from 
500  pounds  to  5  tons,  although  for  sizes  above  3  tons  we  prefer 
the  construction  shown  by  Fig.  49. 

Each  of  the  several  members  composing  the  frame  of  this 
crane  consists  of  a  single  wrought  iron  I-beam,  suitably  connected 
at  the  intersections.  Where  the  height  of  room  admits  of  it,  the 
construction  shown  in  the  cut  is  employed,  the  jib  being  reinforced 
by  a  tension  rod  above,  so  that  there  is  no  brace  below  to  inter- 
fere with  the  motion  of  the  load  upon  the  jib.  When  necessary 
for  the  jib  to  be  close  under  the  ceiling  of  the  room,  a  diagonal 
brace  is  substituted  for  the  tension  rod,  as  explained  on  page  82, 
the  appearance  of  the  crane  then  being  similar  to  that  shown  by 
Fig.  46.  In  this  case,  however,  the  trolley  cannot  move  nearer  to 
the  mast  than  the  intersection  of  the  brace  with  the  jib.  Where 
it  is  desirable  that  the  jib  should  intersect  the  mast  near  the  top 
of  the  latter,  and  the  travel  of  the  trolley  on  the  jib  extend  close 
to  the  mast,  resort  must  be  had  to  the  modes  of  construction 
shown  by  Figs.  49  and  50. 

The  hoisting  mechanism  consists  of  a  pocketed  chain  wheel, 
driven  by  spur  gearing,  and  having  a  safety  device  consisting  of 
an  automatic  friction  ratchet,  so  that  the  load  is  always  self -sus- 
tained in  any  position  and  cannot  run  down.  Lowering  is  effected 
by  reversing  the  motion  of  the  cranks,  and  ceases  automatically 
whenever  this  motion  is  discontinued. 


ii4  A    Treatise  on  Cranes. 

Rotation  of  the  crane  is  effected  by  pushing  or  pulling  the 
suspended  load,  the  construction  of  the  top  and  bottom  pintles 
being  such  as  to  reduce  friction  to  a  minimum.  Motion  of  the 
trolley  is  effected  by  the  independent  gear  attached  to  the  jib 
near  the  mast  and  operated  by  the  endless  hand  chain  shown  in 
the  cut. 

This  crane  is  adapted  to  the  same  uses  as  the  one  previously 
described  and  has  greater  convenience  by  reason  of  the  addition 
of  the  trolley  gear.  It  is  particularly  serviceable  over  lathes, 
planers,  etc.,  and  for  erecting  light  machine  work,  and  in  forges, 
boiler  shops  and  similar  places. 

Estimates  will  be  furnished  on  receipt  of  information  stating 
maximum  load  to  be  lifted,  height  from  floor  to  ceiling,  effective 
radius  desired,  and  the  mode  of  bracing  preferred.  (See  page  82). 


Jib  Cranes.  1 1  5 


JIB   CRANE. 

DOUBLE    IRON    FRAME. — INDEPENDENT    TROLLEY    TRAVEL. 

Fig.  49  represents  a  jib  crane  of  medium  size,  each  member 
of  the  frame  consisting  of  two  parts,  separated  so  as  to  permit  the 
chain  and  block  to  pass  between  them,  so  that  the  load  can  be 
moved  close  in  to  the  mast.  The  hoisting  mechanism  is  attached 
to  the  mast  near  its  foot,  and  the  running  block,  which  carries  the 
load,  is  suspended  from  a  trolley  traveling  on  the  jib  and  capable 
of  movement  in  and  out  by  means  of  independent  gearing 
attached  to  the  jib  at  its  intersection  with  the  mast. 

Cranes  of  this  design  are  built  of  any  desired  capacity  from 
i  ton  to  5  tons.  For  larger  sizes  the  construction  shown  by  Fig. 
50  is  preferred. 

The  frame  consists  of  wrought  iron  channel  beams,  each  of 
the  three  members  of  the  frame  being  composed  of  two  such 
channel  irons.  The  dimensions  are  such  as  to  give  the  accepted 
factor  of  safety  (see  page  83),  and  the  several  parts  are  very 
securely  connected  together  at  their  intersections  by  riveting. 

Hoisting  is  effected  through  a  train  of  spur  gearing,  operated 
by  crank  in  the  usual  way,  and  provided  with  an  automatic  safety 
ratchet.  Lowering  is  effected  by  a  separate  mechanism  consist- 
ing of  a  turned  worm  wheel  and  worm,  operated  by  a  light  hand 
wheel,  as  shown  in  the  cut,  this  mechanism  being  also  available 
for  raising  light  loads.  Thus  arranged,  the  machine  is  self- 
sustaining  and  can  be  left  at  any  time  with  the  load  in  suspension 
without  danger  of  the  load  running  down  or  the  handles  flying 
back.  The  construction  gives  three  changes  of  speed,  and  em- 
bodies the  endless  chain  system  described  at  page  67,  which  insures 
an  even  distribution  of  wear  over  the  entire  length  of  chain. 


n6 


A  Treatise  on  Cranes. 


FIG.  49.— Jib  Crane,  with  Separate  Trolley  Gear. 


Jib  Cranes.  1 1 7 

Rotation  is  easily  effected  by  pushing  or  pulling  the  sus- 
pended load,  the  pintles  in  top  and  bottom  bearings  being  of 
steel  and  turning  in  bronze  boxes.  Motion  of  the  trolley  on  the 
jib,  in  either  direction,  is  effected  by  gearing  operated  from  below 
by  an  endless  hand  chain,  as  shown  in  the  cut.  The  self-sustain- 
ing construction  of  the  hoisting  gear  holds  the  load  suspended 
at  any  height  while  the  trolley  is  moved  in  and  out  on  the  jib. 

Cranes  of  this  type  are  adapted  for  use  in  machine  shops, 
for  handling  and  erecting  work,  in  boiler  shops,  foundries,  forges, 
rolling  mills,  etc. 

Estimates  will  be  furnished  on  receipt  of  information  stating 
maximum  load  to  be  lifted,  height  from  floor  to  ceiling,  effective 
radius  required,  and  mode  of  bracing  preferred.  (See  page  82). 


Jib  Cranes.  1 1 9 


JIB  CRANE. 

DOUBLE    IRON    FRAME. — COMBINED    HOIST    AND  TROLLEY   TRAVEL. 

Fig.  50  represents  a  heavy  Jib  Crane,  with  wrought  iron  frame, 
each  member  of  which  is  double,  so  as  to  permit  the  block  and 
chain  to  pass  between  the  two  sides  of  the  brace.  The  load  is 
carried  by  a  running  block  suspended  from  a  trolley  traveling  in 
and  out  upon  the  jib,  and  all  of  the  operating  mechanism  is  attached 
to  the  mast  near  its  foot.  Cranes  of  this  construction  are  built 
with  capacities  of  from  3  tons  to  12  tons  for  operation  by  hand, 
and  of  any  desired  capacity  for  operation  by  power. 

The  frame  consists  usually  of  wrought  iron  channel  beams, 
each  of  the  three  members  of  the  frame  being  composed  of  two 
such  channel  irons.  The  main  chain  passes  downward  from  the 
trolley  between  the  two  irons  forming  the  jib,  so  that  the  trolley 
may  be  moved  close  in  against  the  mast.  Where  the  load  to  be 
carried,  or  the  dimensions  required  are  such  that  channel  irons 
are  not  available,  resort  is  had  to  plate  girders,  similar  to  those 
used  for  the  bridges  of  large  traveling  cranes,  as  explained  on 
page  83.  The  dimensions  of  the  several  members  of  the  crane 
are  such  as  to  give  the  accepted  factor  of  safety  (see  page  83)  and 
the  parts  are  firmly  united  at  their  intersections  by  gusset  plates 
and  riveting. 

The  operating  mechanism  of  this  crane  is  wholly  contained 
within  the  two  housings  at  the  foot  of  the  mast.  It  consists  of 
worm  wheels,  driven  by  turned  steel  worms  running  in  oil,  and  pro- 
vided with  automatic  friction  ratchets  which  hold  the  load  always 
suspended,  so  that  it  is  self-sustained  and  cannot  run  down  or 
cause  flying  back  of  the  handles.  The  same  mechanism  is  utilized 
for  hoisting  and  lowering,  and  for  causing  travel  of  the  trolley, 
its  mode  of  action  being  fully  described  on  page  65,  to  which 


I2O  A   Treatise  on  Cranes. 

reference  is  made  for  a  description  of  the  method  of  hoisting  and 
lowering,  and  of  moving  the  trolley.  As  there  explained,  either 
crank  may  be  used  for  hoisting  or  for  lowering.  If  both  are 
turned  simultaneously  in  the  same  direction  the  speed  will  be 
doubled,  and  many  men  can  conveniently  apply  their  strength. 
By  placing  the  crank  upon  the  center  shaft,  which  carries  the 
large  gear  wheel,  a  rapid  motion  is  obtained  for  lowering,  or  for 
raising  the  empty  block.  By  engaging  both  pinions  with  the 
large  center  wheel,  which  is  easily  and  quickly  done  by  two  levers 
not  shown  in  the  cut,  and  then  applying  the  crank  to  any  of  the 
shafts,  the  trolley  is  caused  to  travel  in  either  direction  desired, 
the  load  remaining  suspended  at  a  uniform  height.  By  this  mode 
of  operating  the  trolley  the  chains  between  it  and  the  block  do 
not  render  over  their  sheaves  when  the  trolley  moves,  as  is  the 
case  when  an  independant  trolley  mechanism  is  employed, 
thus  avoiding  all  needless  friction  and  wear  of  the  hoisting 
chain  and  also  distributing  the  wear  upon  the  chain  uniformly 
over  its  entire  length,  as  explained  on  page  67,  thereby 
greatly  increasing  its  durability.  Lowering  is  effected  by  rotating 
either  or  both  of  the  cranks  backward,  and  will  continue  so  long 
as  this  motion  of  the  cranks  is  maintained.  If  it  be  discontinued, 
or  if  the  cranks  be  let  go,  the  load  comes  to  rest  and  remains 
automatically  suspended.  Three  changes  of  speed  for  hoisting 
and  lowering  are  obtained,  and  two  for  traversing  the  trolley.  The 
details  of  this  mechanism  are  described  at  page  69. 

The  swinging  or  rotation  of  the  crane  is  effected  by  simply 
pushing  or  pulling  the  suspended  load.  The  top  and  bottom 
bearings  are  bushed  with  bronze,  and  the  pins  or  pivots  are  of 
steel,  turned,  with  ample  provision  for  lubrication,  so  that  friction 
is  reduced  to  a  minimum.  In  cranes  of  large  size  the  chain 
sheaves  in  the  running  block  and  trolley  have  anti-friction  bush- 
ings, as  described  on  page  95. 

This  type  of  crane  is  adapted  to  heavy  work  of  all  kinds, 
in  erecting  shops,  foundries,  forges,  rolling  mills,  stone  sheds, 
etc.  When  arranged  for  operation  by  power  its  capacity  can 
be  indefinitely  extended,  and  proposals  for  power  jib  cranes  will 
be  furnished  on  application. 


Jib  Cranes.  121 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
maximum  load  to  be  lifted,  height  from  floor  to  roof,  effective 
radius  desired,  and  preference,  if  any,  as  to  position  of  brace, 
also  as  to  whether  for  operation  by  hand,  power  or  steam.  (See 
page  82). 


Column  Crane.  123 


COLUMN  CRANE. 

DOUBLE    IRON    FRAME.  —  TURNING    AROUND    FIXED    SUPPORTING 

COLUMN. 

Fig.  51  represents  a  jib  crane,  of  essentially  the  same  con- 
struction as  that  described  on  page  115,  but  arranged  to  revolve 
around  a  fixed  center  column  within  the  mast,  the  column  being 
utilized  for  supporting  the  floor  above.  This  type  of  crane  is 
built  of  any  desired  capacity  from  i  ton  to  10  tons,  although  for 
capacities  above  5  tons  it  is  best  if  possible  to  arrange  the  cranes 
independently  of  the  supporting  columns. 

The  mast  consists  of  two  wrought  iron  channel  beams,  se- 
curely fitted  to  heavy  castings  at  top  and  bottom,  each  of  which 
latter  contains  horizontal  rollers,  traveling  upon  turned  paths  on 
the  center  column,  the  lower  or  foot  casting  being  provided  also 
with  vertical  rollers,  traveling  upon  a  circular  path  around  the 
foot  of  the  column.  The  vertical  rollers  carry  the  weight  of  the 
crane  and  load,  while  the  horizontal  thrust  at  top  and  bottom  is 
received  upon  the  horizontal  rollers.  Thus  arranged  the  rotation 
of  the  crane  is  as  smooth  and  easy  as  that  of  a  crane  turning  upon 
pintles  in  the  usual  way. 

All  of  the  other  details  of  this  crane  being  precisely  similar 
to  those  described  on  pages  115  to  117,  reference  is  made  to  that 
description,  which  will,  therefore,  not  be  repeated  here. 

This  type  of  crane  is  designed  especially  for  use  in  buildings 
where  an  upper  floor  is  supported  upon  columns  which  cannot  be 
removed,  and  around  which  it  is  therefore  desirable  that  the 
cranes  should  rotate.  Thus  arranged  they  have  all  the  con- 
venience and  applicability  of  ordinary  jib  cranes. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
the  maximum  load  to  be  lifted,  height  from  floor  to  ceiling,  effect- 
ive radius  desired,  and  distance  from  center  to  center  of  column, 
where  they  are  so  near  as  to  limit  the  sweep  of  the  crane.  By 
limiting  the  latter  to  less  than  an  entire  revolution,  the  jib  may  be 
lengthened  so  as  to  extend  beyond  the  adjacent  column. 


Walking  Crane.  125 


WALKING  CRANE. 

FOR    OPERATION    BY    POWER    OR    HAND. 

Fig.  52  represents  a  walking  crane  operated  by  power  and 
consisting  of  a  boom,  rotating  around  a  fixed  column  mounted 
upon  an  extended  truck,  which  latter  travels  upon  a  suitable  rail 
upon  the  floor.  Power  is  utilized  for  hoisting  and  lowering,  and 
for  propelling  the  crane  longitudinally  upon  its  track.  Cranes  of 
this  type  are  built  of  any  desired  capacity  from  i  to  10  tons,  and 
for  operation  either  by  hand  or  by  power. 

The  base  consists  of  two  wrought  iron  girders  united  by  riv- 
eting and  carrying  between  them  the  truck  wheels  which  support 
the  crane.  Rising  from  the  center  of  the  base  is  a  cast  iron  col- 
umn, somewhat  similar  to  that  of  the  pillar  crane  shown  on  page 
132,  and  revolving  around  this  is  the  mast,  consisting  of  two 
channel  irons,  united  by  suitable  castings  at  top  and  bottom,  and 
containing  the  rollers  by  which  the  mast  is  supported  as  it  re- 
volves. The  boom  is  also  formed  of  two  channel  irons,  and  from 
its  outer  end  is  suspended  the  running  block,  the  chain  from 
which  passes  over  a  sheave  at  the  end  of  the  boom  to  the  hoisting 
gear  attached  to  the  mast  near  its  head,  the  slack  chain  falling 
from  this  to  a  receptacle  at  the  foot  of  the  boom. 

The  mechanism  of  this  crane,  when  operated  by  power,  is 
arranged  as  shown  in  the  engraving.  Power  is  transmitted  by  a 
driving  rope  passing  around  a  wheel  on  top  of  the  vertical  shaft 
forming  the  axis  of  the  crane,  this  shaft  thus  moving  continuously 
in  one  direction  at  a  constant  speed.  By  a  series  of  Weston  Disc 
Clutches,  controlled  by  suitable  levers  within  easy  reach  of  the 
operator,  the  power  is  made  available  for  hoisting  and  lowering, 
and  for  propelling  the  crane  in  either  direction  upon  its  track. 
Rotation  of  the  crane  is  effected  in  the  usual  way  by  pushing  or 
pulling  the  suspended  load.  The  levers  are  so  arranged  that  the 


126  A    Treatise  on  Cranes. 

operator  may  either  walk  beside  the  crane  as  it  moves,  or  may 
travel  upon  it.  The  crane  is  supported  longitudinally  by  the  ex- 
tended wheel  base  of  the  truck,  and  transversely  by  rails  bolted 
to  the  roof  or  ceiling,  between  which  travels  the  horizontal  truck 
or  guide  frame  attached  to  the  head  of  the  mast. 

When  arranged  for  operation  by  hand,  the  hoisting  gear  of 
this  crane  is  similar  to  that  of  the  pillar  crane  described  on  pages 
133  and  134,  and  the  longitudinal  travel  of  the  crane  is  effected 
by  a  separate  crank,  operating  mechanism  attached  to  the  base. 
The  system  of  .clutches  employed  is  explained  at  page  41. 

Cranes  of  this  type  are  adapted  for  use  in  machine  shops,  for 
setting  work  in  the  various  machine  tools  and  for  transferring  it 
from  one  tool  to  another,  and  also  in  erecting  shops  for  transfer- 
ring parts  to  the  place  of  erection  and  for  setting  them  in  posi- 
tion. For  work  of  this  description  these  cranes  are  exceedingly 
convenient  and  economical. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
whether  to  be  operated  by  hand  or  power,  maximum  load  to  be 
lifted,  effective  radius  desired,  length  of  longitudinal  travel  and 
height  from  floor  to  ceiling. 


Rotary  Bridge  Crane.  127 


ROTARY  BRIDGE  CRANE. 

DOUBLE  IRON  FRAME. — COMBINED  HOIST  AND  TROLLEY  TRAVEL. 

Fig.  53  represents  a  novel  form  of  rotary  crane  and  one 
which  possesses  many  advantages  for  certain  kinds  of  work.  It 
consists  of  a  mast  and  jib,  as  in  an  ordinary  jib  crane,  but  is  pro- 
vided with  a  circular  overhead  track  carrying  the  outer  end  of  the 
jib,  or  rotary  bridge,  so  that  the  latter  may  easily  have  a  much 
greater  length  than  the  jib  of  an  ordinary  jib  crane,  and  so  that 
all  diagonal  braces  are  dispensed  with  and  the  entire  space  under 
the  bridge  left  unobstructed.  Cranes  of  this  construction  are 
built  of  capacities  from  3  to  12  tons  for  operation  by  hand, 
and  of  any  desired  capacity  for  operation  by  power. 

The  frame  consists  usually  of  wrought  iron  channel  beams,  the 
mast  and  the  bridge  each  being  composed  of  two  such  channel 
irons.  The  operating  mechanism,  for  operation  by  hand,  is  con- 
tained wholly  within  the  two  housings  at  the  foot  of  the  mast,  and 
its  construction  and  action  are  identical  with  those  of  the  jib  crane 
described  on  pages  1 1 9  to  1 2 1 ,  to  which  reference  is  made  for  further 
particulars.  The  same  mechanism  is  utilized  for  hoisting  and 
lowering  at  several  speeds,  and  for  causing  travel  of  the  trolley 
in  either  direction  upon  the  bridge.  Rotation  is  effected  by  sim- 
ply pushing  or  pulling  the  suspended  load,  except  in  cranes  of 
large  size,  which  are  provided  with  a  power  mechanism  for  this 
purpose.  The  construction  of  the  upper  bearing  of  the  crane, 
by  which  the  head  of  the  mast  is  carried,  is  such  as  to  avoid  any 
severe  lateral  strains  upon  the  roof,  the  weight  being  carried,  at 
one  end  of  the  bridge,  by  the  mast,  and  at  the  other  by  the  cir- 
cular track,  which  is  supported  from  the  ground  by  suitable  posts. 

This  type  of  crane  affords  all  the  conveniences  of  the  ordi- 
nary jib  crane,  while  avoiding  the  limitation  in  the  vertical  move- 
ments of  the  load  imposed  by  the  diagonal  braces  of  the  latter. 


Rotary  Bridge  Crane.  129 

It  also  avoids  the  severe  lateral  strains  upon  the  building  which 
result  from  the  use  of  jib  cranes,  and  thus  dispenses  with  the 
heavy  walls  or  bracing  necessary,  where  jib  cranes  are  employed, 
to  afford  the  proper  support  of  the  upper  end  of  the  mast  of  such 
cranes.  The  posts  supporting  the  circular  track  can  easily  be 
so  placed  as  to  cause  little  if  any  obstruction  upon  the  floor,  or, 
if  the  roof  be  stiff  enough,  the  track  may  be  hung  directly  from  it 
without  resorting  to  special  posts.  The  bridge,  being  supported 
at  both  ends,  can  conveniently  have  much  greater  span  than  the 
jib  of  a  jib  crane,  the  outer  end  of  which  is  necessarily  overhung. 
With  rotary  bridge  cranes  of  ordinary  capacity  a  span  of  50  feet 
is  entirely  feasible,  and  in  this  way  the  crane  can  be  made  to  cover 
a  circular  floor  100  feet  in  diameter. 

Cranes  of  this  type  are  adapted  to  heavy  and  light  work  of  all 
kinds,  especially  in  foundries,  erecting  shops,  stone  sheds,  etc. 
When  arranged  for  operation  by  power  their  capacity  can  be  in- 
definitely extended.  They  are  particularly  applicable  to  existing 
buildings  the  shape  of  which  does  not  adapt  them  to  the  applica- 
tion of  traveling  cranes,  and  in  which  the  construction  does  not 
adequately  provide  for  the  strains  which  would  result  from  the 
use  of  jib  cranes. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
whether  to  be  operated  by  hand,  power  or  steam,  the  maximum 
load  to  be  lifted,  height  from  floor  to  roof,  effective  radius  desired, 
and  such  particulars  concerning  the  building  as  will  give  a  clear 
understanding  of  the  situation. 


Derrick  Crane.  131 


DERRICK  CRANE. 

IRON    FRAME. WITH    TROLLEY    MOTION. 

Fig.  54  represents  a  heavy  derrick  crane  for  outdoor  use,  the 
construction  being  substantially  identical  with  that  of  the  jib  crane 
illustrated  by  Fig.  5  o,  except  that  the  head  of  the  mast  is  sup- 
ported by  guy  rods,  instead  of  by  attachment  to  a  roof  or  ceiling. 
This  style  of  crane  is  built  of  capacities  from  5  to  20  tons,  and 
of  any  desired  dimensions  of  mast  and  jib. 

The  description  on  pages  119  to  121  of  the  jib  crane  therewith 
illustrated  will  apply  to  this  crane  also,  all  of  their  several  parts  being 
identical,  except  that  in  this  case  the  mast  is  extended  somewhat 
above  the  jib,  and  the  upper  bearing,  in  which  the  mast  revolves, 
is  supported  laterally  by  guy  ropes,  or  rods,  attached  at  their  lower 
ends  to  suitable  anchors  in  the  ground,  or  to  adjacent  buildings. 
The  motions  of  hoisting  and  lowering,  and  travel  of  the  trolley  on 
the  jib,  are  all  effected  by  means  of  the  mechanism  at  the  foot  of 
the  mast.  By  pushing  or  pulling  the  suspended  load  rotation  of 
the  crane  is  effected  as  easily  as  in  the  case  of  the  ordinary  jib 
crane. 

This  crane  is  adapted  for  use  in  freight  yards,  quarries,  and 
on  wharves,  and  can  be  substituted  for  the  pillar  crane  shown  on 
page  132,  where  the  guy  rods  are  not  objectionable,  or  where  there 
is  difficulty  in  obtaining  the  foundation  needed  to  support  a  pillar 
crane.  It  can  also  be  arranged  for  operation  by  power,  or  by 
direct  steam. 

Estimates  will  be  furnished  on  receipt  of  information  stating 
whether  to  be  operated  by  hand,  power  or  steam,  maximum  load 
to  be  lifted,  effective  radius  of  jib  required,  and  particulars  as 
to  surrounding  buildings,  if  any,  which  are  available  for  attach- 
ment of  guys. 


, 


Pillar  Cranes.  133 


PILLAR  CRANE. 

SUPPORTED    BY    FOUNDATION    ONLY. 

Fig.  55  represents  a  pillar  crane  which  is  supported  entirely 
by  a  suitable  foundation,  of  masonry  or  timber,  to  which  the 
central  pillar  or  column  is  securely  bolted,  the  boom  being  sup- 
ported by  this  column  and  rotating  around  it.  This  style  of 
crane  is  built  of  any  desired  capacity  from  i  ton  upwards,  and  of 
any  desired  radius. 

As  this  crane  is  supported  entirely  from  below,  without  any 
assistance  from  overhead  braces  or  attachments,  it  requires  a 
heavy  foundation,  of  sufficient  mass  and  weight  to  firmly  resist  the 
overturning  tendency  of  the  load  when  suspended  at  the  outer 
end  of  the  boom.  The  proper  construction  of  this  foundation  is 
explained  in  Part  II,  pages  97  and  98.  As  there  shown  it  consists  of 
rubble  masonry  built  on  a  suitable  foundation  and  covered  with  a 
cap  stone  immediately  under  the  base  of  the  iron  column.  A  heavy 
foundation  plate  and  holding  down  bolts  are  set  in  the  masonry 
and  the  latter  built  around  them,  the  bolts  passing  through  the 
cap  stone  and  serving  to  rigidly  fasten  the  column  of  the  crane  to 
the  foundation,  as  shown  in  the  illustration.  A  drawing  of  the 
necessary  foundation  is  furnished  to  parties  ordering  cranes  of 
this  kind. 

The  pillar  or  column  of  the  crane  is  of  cast  iron,  and  of  simple 
but  symmetrical  design,  its  form  being  proportioned  to  the  strains 
it  has  to  resist.  It  has  a  broad  base,  thus  giving  it  a  good  footing 
on  the  foundation  and  spreading  the  holding  down  bolts  well 
apart.  Fixed  in  the  head  of  the  column  is  a  steel  pin  or  pivot 
upon  which  rests  the  cross  head  or  yoke.  The  latter  is  bushed 
with  bronze  and  has  proper  provision  for  lubrication,  so  that  the 
cross-head  shall  always  turn  freely  on  the  pin.  The  boom  or 
strut  consists  of  two  wrought  iron  channel  beams,  well  braced  to- 


134  ^    Treatise  on  Cranes. 

gether  and  united  at  the  upper  end  by  a  head  casting  carrying 
the  upper  chain  sheaves  over  which  the  chain  passes  to  the  run- 
ning block.  The  foot  of  the  boom  is  supported  vertically  by  two 
suspension  rods,  hung  from  the  ends  of  the  cross-head,  and  its 
upper  end  or  head  is  held  by  two  guy  rods,  also  extending  back 
to  the  cross-head.  The  horizontal  thrust  at  the  foot  of  the  boom 
is  transmitted  to  two  turned  rollers,  placed  within  the  foot  casting 
of  the  boom  and  traveling  upon  a  turned  path  around  the  base  of 
the  column.  The  weight,  both  of  the  boom  and  load,  is  entirely 
carried  by  the  steel  pin  at  the  top  of  the  column,  and  the  friction 
of  rotation  is  thus  reduced  to  a  minimum. 

The  hoisting  gear  is  attached  to  the  boom  near  the  column 
and  rotates  with  the  former.  It  consists  of  a  train  of  spur  gearing 
provided  with  an  automatic  safety  ratchet  and  with  the  Weston 
Disc  Brake  for  lowering,  substantially  as  in  the  jib  crane  described 
on  pages  115  to  117,  so  that  the  load  is  always  self-sustained  and 
cannot  run  down,  nor  the  handles  recoil  on  the  operator.  Lower- 
ing is  effected  by  turning  the  cranks  backward,  the  load  descending 
easily  and  smoothly  so  long  as  this  motion  is  continued,  but  com- 
ing to  rest  if  the  backward  motion  be  discontinued  or  the  handles 
let  go.  Two  changes  of  speed  are  provided.  Swinging  or  rota- 
tion of  the  crane  is  effected  by  pushing  or  pulling  the  suspended 
load,  and  the  construction  is  such  that  the  maximum  load  can  be 
easily  swung  by  one  man. 

This  type  of  crane  is  designed  for  yard  use  where  there  is  no 
roof  or  ceiling  to  support  the  top  of  crane,  and  where  guy  rods, 
as  shown  by  Fig.  54,  are  objectionable.  It  is  particularly  adapted 
to  railroad  and  wharf  use,  for  loading  and  unloading  heavy  work 
from  cars  or  boats,  and  is  a  useful  addition  to  the  yard  appli- 
ances of  any  large  works.  They  are  constructed  for  operation  by 
hand,  by  power  or  by  direct  steam,  according  to  the  requirements 
of  the  case. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
maximum  load  to  be  lifted,  effective  radius  desired,  and  source  of 
motive  power,  if  other  than  manual. 


Locomotive  Cranes.  135 


•  LOCOMOTIVE  CRANE. 

SELF-PROPELLING. 

Cranes  of  this  type  consist  of  a  rotary  crane,  usually  of  the 
pillar  variety,  as  shown  by  Fig.  55,  mounted  upon  a  suitable  car 
or  truck,  and  provided  with  an  independent  boiler  and  engine, 
the  power  of  which  is  utilized  for  hoisting,  lowering  and  rotating 
the  load,  and  also  for  propelling  the  car  upon  its  tracks. 

Locomotive  cranes  are  of  great  convenience  in  large  works 
of  all  kinds  where  the  buildings  cover  much  ground  and  are  con- 
nected by  means  of  railroad  tracks.  By  means  of  these  tracks 
the  crane  can  be  transferred  from  one  place  to  another,  to  suit 
the  requirements  of  the  work,  and  can  be  utilized  also  for  trans- 
ferring heavy  loads  from  one  building  to  another.  They  are  use- 
ful also  upon  freight  wharves  where,  by  means  of  a  track  laid  near 
the  edge  of  the  wharf,  they  can  be  utilized  for  unloading  vessels 
and  also  for  transferring  heavy  loads  from  one  vessel  to  another. 

The  construction  of  cranes  of  this  type  is  varied  according 
to  the  requirements  of  the  work  to  be  done,  but  they  embody  in 
one  form  or  another  the  same  arrangements  and  details  as  the 
other  cranes  described  in  this  book. 

Estimates  for  locomotive  cranes  will  be  submitted  upon  re- 
ceipt of  information  as  to  the  maximum  load  to  be  lifted,  the 
effective  radius  desired,  the  gauge  of  track  on  which  the  crane 
should  travel,  and  other  particulars  as  to  the  nature  of  the  work 
to  be  done. 


Bridge  Cranes.  137 


BRIDGE  CRANE. 

IRON    FRAME. FOR    OPERATION    BY    HAND    OR    POWER. 

Fig.  56  represents  a  crane  for  yard  use  consisting  of  a  sta- 
tionary bridge,  supported  at  each  end  by  a  suitable  trestle,  and 
provided  with  a  trolley  moving  transversely  on  the  bridge.  The 
load  is  carried  by  a  running  block  suspended  from  the  trolley, 
and  the  mechanism  for  hoisting  and  traversing  is  attached  to  one 
of  the  vertical  frames  or  trestles  near  its  foot.  Cranes  of  this 
construction  are  built*  of  capacities  of  from  2  to  12  tons  for 
operation  by  hand,  and  of  any  desired  capacity  for  operation  by 
power. 

Fig.  57  represents  another  form  of  bridge  crane,  in  which 
one  end  of  the  bridge  is  supported  by  a  building  and  the  outer 
end  by  a  frame  or  trestle,  so  that  the  frame  is  available  for  trans- 
ferring weights  into  or  out  of  the  building.  In  some  cases  a  crane 
of  this  type  is  placed  between  two  adjoining  buildings,  its  ends 
being  supported  by  the  adjacent  walls  of  each  building  ;  while  in 
other  cases  the  bridge  of  the  crane  is  carried  through  the  door- 
way of  a  building,  so  that  the  load  can  be  transferred  from  a 
truck  or  car  outside  of  the  building  to  some  point  within  it. 

The  crane  shown  by  Fig.  56  is  arranged  for  operation 
by  hand,  and  is  built  entirely  of  iron.  It  is  provided  with 
mechanism  substantially  identical  with  that  of  the  jib  crane 
described  on  page  119,  to  which  reference  is  made  for  further 
particulars.  The  same  mechanism  is  utilized  for  hoisting  and  low- 
ering at  several  speeds,  and  for  causing  the  trolley  to  travel  upon 
the  bridge. 

The  crane  shown  in  Fig.  57  is  arranged  for  operation  by 
power,  the  operating  mechanism  being  located  within  the  building 
and  driven  by  power  taken  from  the  line  shafting.  The  levers 
for  controlling  the  several  motions  are  placed  upon  the  wall  of 


Bridge  Cranes.  139 

the  building  at  any  convenient  point  within,  and  arranged  so  that 
they  may  be  used  from  either  of  the  several  floors.  The  operating 
mechanism  is  substantially  identical  with  that  employed  in  the 
power  traveling  cranes  described  on  page  155,  the  details  being 
more  particularly  described  in  Part  II,  page  73. 

Cranes  of  this  type  are  available  for  yard  uses  of  all  kinds  in 
connection  with  foundries,  machine  shops,  quarries,  etc.  They 
are  particularly  available  for  loading  and  unloading  heavy  freight 
from  cars,  and  are  an  excellent  substitute  for  the  pillar  crane  illus- 
trated by  Fig.  55.  As  compared  with  the  latter  they  have  the 
advantage  of  not  requiring  any  foundation  except  that  necessary 
to  resist  the  direct  pressure  due  to  the  load.  They  may  be  made 
to  span  two  or  more  tracks  and  are  thus  available  for  transferring 
loads  from  one  car  to  another,  or  from  a  car  to  a  truck  or  plat- 
form. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
whether  to  be  operated  by  hand  or  power,  the  maximum  load  to 
be  lifted,  the  height  of  bridge  above  ground,  the  length  between 
supports,  and  particulars  as  to  mode  of  supporting  the  bridge, 
that  is,  whether  by  independent  frames  or  by  the  walls  of  buildings. 


140 


A  Treatise  on  Cranes. 


Hand  Traveling  Cranes.  141 


HAND  TRAVELING  CRANE. 

FOR     DIFFERENTIAL     PULLEY     BLOCK. LONGITUDINAL    TRAVERSE 

GEAR    ONLY. 

Fig.  58  represents  a  light  traveling  crane,  for  operation  by 
hand,  in  which  the  hoisting  mechanism  consists  of  a  Weston  Dif- 
ferential Pulley  Block  suspended  from  the  trolley. 

The  bridge  is  arranged  to  travel  lengthwise  upon  the  longi- 
tudinal tracks,  and  the  trolley  to  move  transversely  upon  the 
bridge,  so  that  the  entire  rectangular  space  between  the  tracks  is 
covered  by  the  crane.  If  desired,  several  trolleys  and  blocks  can 
be  fitted  to  the  same  crane.  This  style  of  crane  is  built  of  any 
desired  capacity  from  i  ton  upwards,  and  of  any  desired  span. 

The  mechanism  attached  to  the  right  hand  end  of  the  bridge 
consists  substantially  of  the  bridge-traveling  apparatus  described 
on  pages  58  to  60,  Part  II.  It  is  operated  by  a  single  endless  hand 
rope  or  chain,  reaching  from  the  machine  downward  towards  the 
floor,  by  pulling  one  side  of  which  the  bridge  is  propelled  in  one 
direction  upon  its  tracks,  while  by  pulling  the  opposite  side  the 
bridge  is  propelled  in  the  opposite  direction.  The  Weston  fixed 
cable  system  of  propulsion  is  employed,  and  is  utilized  also  to 
effect  the  squaring  of  the  bridge  with  its  tracks,  as  explained  on 
page  54,  so  that  the  bridge  moves  always  in  parallelism  with  its 
tracks,  and  with  a  minimum  resistance.  For  light  loads  and  short 
spans  the  squaring  device  is  not  essential  (although  it  is  always 
conducive  to  smoother  and  easier  motion),  in  which  case  a  simple 
bridge  without  any  squaring  device  may  be  used.  The  latter  ar- 
rangement, however,  cannot  be  recommended  except  for  very 
short  spans,  and  in  all  other  cases  the  crane  shown  in  Fig.  58  is  to 
be  preferred. 

The  construction  of  the  bridge  is  explained  on  page  85,  the 
bridge  trucks  on  page  78,  and  the  trolley  and  the  Differential 
Pulley  Blocks  in  Part  IV. 


142  A    Treatise  on  Cranes. 

None  of  the  mechanism  projects  more  than  a  few  inches 
above  the  top  of  the  bridge,  so  that  the  latter  may  be  placed  close 
to  the  ceiling  or  roof  timbers  of  the  room,  thus  affording  the 
greatest  possible  height  of  hoist.  The  longitudinal  motions  of 
the  bridge  are  effected  by  pulling  the  hand  rope  as  above  ex- 
plained, and  the  transverse  motion  of  the  trolley  on  the  bridge  by 
pushing  or  pulling  the  suspended  load. 

This  crane  is  especially  adapted  to  light  foundry  work,  to  the 
erection  of  light  machinery,  to  the  setting  of  work  in  lathes, 
planers,  etc.,  and  for  use  over  very  heavy  machines,  such  as  steam 
engines,  rolling  mills,  printing  presses,  etc.,  for  the  removal  and 
handling  of  parts  during  repairs. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
maximum  load  to  be  lifted,  span  or  length  of  bridge,  height  of 
ceiling,  and  length  of  longitudinal  travel. 


Hand  Traveling  Cranes.  143 


HAND  TRAVELING   CRANE. 

FOR      DIFFERENTIAL     PULLEY     BLOCK. — WITH     TRANSVERSE     AND 
LONGITUDINAL    TRAVERSE    GEAR. 

Fig.  59  represents  a  light  Traveling  Crane  for  operation  by 
hand,  in  which,  as  in  Fig.  58,  the  hoisting  mechanism  consists  of 
a  Weston  Differential  Pulley  Block  suspended  from  the  trolley, 
but  which  is  provided  not  only  with  mechanism  for  traversing 
the  bridge  upon  the  longitudinal  tracks,  but  also  with  mechanism 
for  causing  travel  of  the  trolley  upon  the  bridge.  As  shown  in 
the  engraving,  the  Crane  is  provided  with  two  complete  trolleys 
and  blocks,  but  can  of  course  be  furnished  with  one  or  more,  as 
desired. 

In  this,  as  in  the  preceding  illustration,  the  bridge  is  ar- 
ranged to  travel  lengthwise,  and  the  trolley  (whether  one  or 
more)  to  move  transversely  upon  the  bridge,  thus  covering  the 
entire  space  embraced  between  the  tracks.  Cranes  of  this  type 
are  built  of  any  desired  capacity  from  one  ton  upwards,  and  of 
any  desired  span. 

The  mechanism  attached  to  the  right  hand  end  of  the  bridge 
consists  of  the  bridge-traveling  apparatus  described  on  pages  58 
to  60.  It  is  operated  by  a  single  endless  hand  rope  or  chain, 
extending  downward  towards  the  floor,  by  pulling  one  side  of 
which  the  bridge  is  propelled  in  one  direction  upon  its  tracks, 
while  by  pulling  it  on  the  opposite  side  the  bridge  is  propelled  in 
the  opposite  direction.  The  Weston  fixed-cable  system  is  em- 
ployed, both  for  propelling  the  bridge  and  for  squaring  it  with 
its  tracks,  as  explained  at  page  54.  For  light  loads  and  short 
spans  the  squaring  device  is  not  essential,  although  always  con- 
ducive to  smoother  action,  in  which  case  a  simple  bridge,  with- 
out squaring  device,  may  be  used.  The  latter  arrangement, 
however,  is  not  recommended  except  for  short  spans  and  light 
loads. 


144 


A    Treatise  on  Cranes. 


FIG.  59. — Light  Hand  Traveling  Crane. 


Hand  Traveling  Cranes.  145 

As  illustrated  in  the  engraving  the  Crane  is  provided  with 
two  independent  trolleys,  each  having  a  differential  pulley 
block  suspended  from  it.  Thus  arranged,  it  is  particularly  con- 
venient for  lifting  bulky  loads,  or  for  handling  the  heavy  parts  of 
engines  or  other  machinery  which  require  to  be  removed  for 
repairs  or  inspection.  Each  trolley  is  provided  with  independent 
mechanism  for  causing  it  to  travel  upon  the  bridge,  and  is  con- 
trolled by  means  of  a  single  endless  hand  chain  depending  from 
the  trolley,  as  shown  in  the  engraving. 

The  construction  shown  in  the  engraving  is  desirable 
wherever  the  head-room  admits  of  it.  Where  absolutely  necessary, 
however,  the  mechanism  can  be  so  arranged  as  to  occupy  but 
little  more  space  above  the  bridge  than  in  the  crane  shown  by 
Fig.  58.  In  this  case  the  general  appearance  of  the  trolley  is 
somewhat  as  represented  in  Fig.  61.  The  chief  point  of  difference 
between  this  crane  and  the  one  illustrated  in  Fig.  58  consists  in 
the  addition  of  the  mechanism  for  causing  travel  of  the  trolley 
upon  the  bridge  by  means  of  a  hand  chain  operated  from  the 
floor  below,  instead  of  by  pushing  or  pulling  the  suspended  load. 

This  crane  is  adapted  to  the  same  range  of  uses  as  stated  in 
connection  with  the  crane  illustrated  by  Fig.  58,  the  addition  of 
traverse  gear  making  it  more  desirable  where  heavy  loads  are  to 
be  handled. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
maximum  load  to  be  lifted,  span  or  length  of  bridge,  height  of 
ceiling,  and  length  of  longitudinal  travel. 


146 


A    Treatise  on  Cranes. 


Hand  Traveling  Cranes.  147 


HAND   TRAVELING  CRANE. 

COMBINED    TROLLEY  (HIGH   PATTERN)  WITH    COMPLETE    HOISTING 
AND    TRAVELING    GEAR. 

The  illustration  on  opposite  page  represents  a  complete 
traveling  crane,  arranged  for  operation  by  hand  from  the  floor 
below,  the  operating  mechanism  being  contained  entirely  within 
a  trolley-crab,  placed  on  top  of  the  bridge  and  moving  transversely 
upon  it.  This  location  of  the  trolley  is  to  be  preferred  wherever 
the  head  room  within  the  building  admits  of  it.  Two  or  more 
trolleys  may  be  placed  upon  the  same  bridge.  The  bridge  is 
arranged  to  travel  lengthwise  upon  the  longitudinal  tracks,  and 
the  trolley  to  move  transversely  upon  the  bridge,  so  that  the  en- 
tire rectangular  space  between  the  tracks  is  covered  by  the  crane. 
This  design  of  crane  is  built  of  any  desired  capacity  up  to  10 
tons,  and  of  any  span. 

The  squaring  of  the  bridge,  and  its  motion  upon  the  longi- 
tudinal tracks,  and  also  the  motion  of  the  trolley  upon  the  bridge, 
are  all  effected  by  the  Weston  system  of  fixed  cables  as  explained 
in  Part  II,  page  6 1.  The  crab  or  housing  containing  the  mechan- 
ism travels  upon  rails  on  top  of  the  bridge,  and  is  located  entirely 
above  the  latter,  so  that  the  breaking  of  any  of  its  parts  will 
merely  allow  them  to  rest  upon  the  bridge  without  permitting 
the  load  to  fall  more  than  a  few  inches.  This  disposition  of 
parts  is  always  desirable  if  the  overhead  space  is  sufficient  to 
admit  of  it,  and  for  this  reason  the  cranes  herewith  illustrated 
should  be  adopted  in  preference  to  the  one  illustrated  by  Fig.  61, 
wherever  the  circumstances  of  the  case  make  it  feasible. 

The  several  operations  are  effected  by  four  endless  hand 
chains  or  ropes  depending  from  the  crab.  Those  at  the  opposite 
sides  of  the  crab  give  motion  to  the  bridge  and  to  the  trolley,  as 
explained  at  page  61.  Those  at  the  ends  of  the  crab  effect 


148  A    Treatise  on  Cranes. 

hoisting  and  lowering,  one  of  them  passing  over  a  small  wheel 
for  quick  speeds,  and  the  other  over  a  larger  one  for  slow  speeds, 
a  third  speed  being  obtained  by  using  both  simultaneously.  The 
hoisting  gear  consists  of  cut  steel  worms,  engaging  with  cut 
worm  wheels,  with  provision  for  thorough  lubrication.  The  main 
hoisting  chain  is  endless,  and  passes  over  pocketed  chain  wheels 
by  which  it  is  driven,  the  arrangement  of  parts  being  such  as  to 
distribute  the  wear  equally  throughout  the  entire  length  of  this 
chain  in  a  manner  somewhat  similar  to  that  described  on 
page  67.  A  safety  device,  consisting  of  automatic  friction  ratchets 
in  combination  with  the  worm  shafts,  is  employed,  so  that 
the  load  is  always  self-sustained  in  any  position  and  cannot  run 
down.  Lowering  is  effected  by  reversing  the  motion  of  the 
hoisting  chains.  For  descriptions  of  the  various  details  of  this 
crane  reference  is  made  to  Part  II. 

This  type  of  crane  is  adapted  to  machine  shop  use,  for  erect- 
ing and  setting  work,  to  forges,  boiler  shops,  stone  yards  and 
other  places  where  heavy  loads  are  to  be  handled.  Where  ap- 
plicable, it  is  the  most  perfect  and  convenient  form  of  crane  for 
operation  by  hand. 

Estimates  will  be  submitted  on  receipt  of  information  as  to 
maximum  load  to  be  lifted,  span  or  length  of  bridge,  height  from 
floor  to  ceiling  or  roof,  and  length  of  longitudinal  travel. 


Hand  Traveling  Cranes.  149 


HAND   TRAVELING  CRANE. 

COMBINED    TROLLEY    (LOW    PATTERN)   WITH    COMPLETE    HOISTING 
AND    TRAVELING    GEAR. 

The  Crane  illustrated  on  next  page  is  of  the  same 
general  character  as  that  in  the  preceding  illustration,  except 
that  the  trolley-crab  and  its  operating  mechanism  are  arranged 
at  each  side  of  and  below  the  bridge,  the  form  of  the  trolley  being 
such  as  to  enable  the  bridge  to  be  placed  close  under  the 
roof  or  ceiling  of  the  room.  Two  or  more  trolleys  maybe  placed 
upon  the  same  bridge.  The  bridge  is  arranged  to  travel  length- 
wise upon  the  longitudinal  tracks,  and  the  trolley  to  move 
transversely  upon  the  bridge,  so  that  the  entire  rectangular  space 
between  the  tracks  is  covered  by  the  crane.  This  type  of  crane 
is  built  of  any  desired  capacity  up  to  10  tons  and  of  any  span. 

The  hoisting  gear  consists  of  cut  steel  worms  engaging  with 
cut  worm  wheels,  with  provision  for  thorough  lubrication.  The 
main  hoisting  chain  is  endless  and  passes  over  pocketed  chain 
wheels  by  which  it  is  driven,  the  arrangement  of  parts  being  such 
as  to  distribute  the  wear  equally  throughout  the  entire  length  of 
this  chain. 

A  safety  device,  consisting  of  automatic  friction  ratchets  in 
combination  with  the  worm  shafts,  is  employed,  so  that  the  load 
is  always  self-sustained  in  any  position,  and  cannot  run  down. 
Lowering  is  effected  by  reversing  the  motion  of  the  hoisting 
chains. 

The  Weston  system  of  fixed  cables  (see  Part  II,  page  61)  is 
employed  to  effect  the  squaring  of  the  bridge  with  its  tracks,  and 
its  propulsion  upon  them,  and  also  to  move  the  trolley  transversely 
upon  the  bridge.  The  operating  mechanism  is  contained  en- 
tirely within  the  trolley,  and  its  motions  are  controlled  by  four 
endless  hand  ropes  or  chains  depending  from  it,  two  of  which 


Hand  Traveling  Cranes.  151 

control  the  motions  of  the  bridge  upon  its  tracks  and  of  the 
trolley  upon  the  bridge,  while  the  other  two  each  effect  hoisting 
or  lowering  (according  to  the  direction  in  which  they  are  pulled) 
at  different  speeds,  a  third  speed  being  obtained  by  simulta- 
neously using  both. 

The  construction  of  the  crab  economizes  room  by  placing 
much  of  the  gearing  between  the  crab  frames  and  the  bridge,  thus 
adapting  the  crane  to  use  in  shops  or  rooms  with  low  ceilings, 
where  the  construction  shown  in  Fig.  60  would  occupy  too  much 
height,  but  the  latter  type  of  crane  is  to  be  preferred  wherever 
the  head  room  admits  of  it.  Reference  is  made  to  Part  II  for 
full  descriptions  of  the  detail  parts  of  this  crane. 

The  cranes  of  this  pattern  are  designed  especially  for  use  in 
machine  shops,  both  for  setting  work  in  machines  and  for  erect- 
ing it,  and  also  in  forges,  mills,  stone  sheds,  and  warehouses  for 
the  storage  of  heavy  goods. 

Estimates  will  be  submitted  on  receipt  of  information  as  to 
the  maximum  load  to  be  lifted,  the  span  or  length  of  bridge, 
height  from  floor  to  ceiling,  and  length  of  longitudinal  travel. 


152 


A    Treatise  on  Cranes. 


Hand  Traveling  Cranes.  153 


HAND  TRAVELING  CRANE. 

FOUNDRY  PATTERN. WITH  COMPLETE  HOISTING  AND  TRAVELING 

GEAR. 

Fig.  62  opposite  represents  a  complete  traveling  crane, 
for  operation  by  hand,  of  a  construction  similar  to  the  two 
preceding  illustrations,  but  with  the  mechanism  attached  to  one 
end  of  the  bridge  so  that  the  operator  is  somewhat  removed  from 
the  load,  thus  adapting  it  especially  to  foundry  use.  The  bridge 
is  arranged  to  travel  lengthwise  upon  the  longitudinal  tracks,  and 
the  trolley  to  move  transversely  upon  the  bridge,  so  that  the  en- 
tire rectangular  space  between  the  tracks  is  covered  by  the  crane. 
Cranes  of  this  design  are  built  of  any  desired  capacity  up  to  10 
tons,  and  of  any  span. 

The  crab  containing  the  operating  mechanism  is  permanently 
secured  to  the  under  side  of  the  bridge  at  one  end,  and  is  located 
entirely  below  it,  so  that  the  bridge  can  be  placed  close  to  the 
under  side  of  roof  or  ceiling.  The  trolley  travels  upon  tracks  on 
top  of  the  bridge,  and  its  sides  extend  downward  close  to  the 
bridge,  with  the  chain  sheaves  contained  between  them,  thus  giv- 
ing the  maximum  amount  of  hoist.  The  Weston  fixed-cable  sys- 
tem (see  Part  II,  page  58)  is  employed  to  effect  the  squaring  of 
the  bridge  and  its  longitudinal  motion  upon  the  overhead  tracks. 
The  travel  of  the  trolley  upon  the  bridge  is  effected,  by  an  inde- 
pendent mechanism,  operated  by  an  endless  hand  chain  from  the 
floor  below,  in  a  manner  similar  to  that  employed  in  the  jib 
cranes  described  on  page  117,  the  details  of  which  are  fully  ex- 
plained in  Part  II,  page  65.  Motion  of  the  bridge  is  also  effected 
by  an  endless  hand  chain  or  rope  passing  over  another  rope 
wheel.  Pulling  one  side  of  this  chain  causes  the  bridge  to 
move  in  one  direction,  and  pulling  the  other  causes  it  to  move  in 
the  opposite  direction.  At  each  end  of  the  crab,  or  housing  con- 


154  ^    Treatise  on  Cranes. 

taining  the  operating  mechanism,  are  similar  rope  wheels,  over 
each  of  which  passes  an  endless  rope  or  chain.  Pulling  either 
of  these  in  one  direction  causes  hoisting,  and  in  the  other  lower- 
ing. One  is  larger  than  the  other,  thus  giving  two  speeds  ;  while, 
by  pulling  both  simultaneously,  an  additional  speed  is  obtained. 
The  several  motions  of  hoisting  or  lowering,  and  of  moving  the 
bridge  and  the  trolley,  may  each  be  effected  independently  or 
simultaneously. 

The  hoisting  gear  consists  of  cut  steel  worms  engaging  with 
cut  worm  wheels,  with  provision  for  thorough  lubrication.  The 
main  hoisting  chain  is  endless  and  passes  over  pocketed  chain 
wheels,  by  which  it  is  driven,  the  arrangement  of  parts  being  such 
as  to  distribute  the  wear  equally  throughout  the  entire  length  of 
this  chain.  A  safety  device,  consisting  of  automatic  friction 
ratchets  in  combination  with  the  worm  shafts,  is  employed,  so 
that  the  load  is  always  self-sustained  in  any  position  and  cannot 
run  down.  Lowering  is  effected  by  reversing  the  motion  of  the 
hoisting  chains. 

The  location  of  the  mechanism  at  one  end  of  the  bridge  re- 
moves the  operator  from  proximity  to  the  load,  which  is  of  course 
desirable  in  handling  ladles  of  hot  metal,  and  in  lifting  large 
flasks,  etc.  For  description  of  the  bridge  construction,  see  page 
85,  of  the  bridge  trucks  page  78,  and  for  other  details  the  several 
articles  in  Part  II. 

While  particularly  designed  for  foundry  use  this  type  of  crane 
is  equally  suitable  for  use  in  forges  and  for  many  of  the  same 
purposes  as  the  cranes  illustrated  by  Figs.  60  and  61. 

Estimates  will  be  furnished  on  receipt  of  information  as  to 
maximum  load  to  be  lifted,  span  or  length  of  bridge,  height  from 
floor  to  under  side  of  roof,  and  length  of  longitudinal  travel. 


Power   Traveling  Cranes.  155 


POWER  TRAVELING   CRANE. 


The  illustration  on  next  page  represents  a  Weston  Traveling 
Crane,  driven  by  power  transmitted  from  a  stationary  source, 
and  controlled  by  an  operator  standing  on  a  platform  suspended 
from  the  crane  at  one  end  of  the  bridge.  The  bridge  is  arranged 
to  travel  longitudinally  upon  overhead  tracks,  and  the  trolley  to 
travel  transversely  across  the  bridge,  so  that  the  efficiency  of  the 
crane  covers  the  entire  rectangle  included  between  the  tracks, 
which  latter  may,  if  desired,  be  400  or  500  feet,  or  more,  in  length. 
Cranes  of  this  construction  are  built  of  any  desired  capacity  from 
5  to  50  tons,  and  of  any  span. 

This  crane  consists  of  a  bridge  composed  of  two  wrought 
iron  girders  (constructed  as  explained  in  Part  II,  page  83)  carried 
at  each  end  by  a  two-wheeled  truck  (for  description  see  page  78) 
with  double-flanged  truck  wheels  having  chilled  treads.  At  one 
end  of  the  bridge  is  a  crab  containing  the  operating  mechanism, 
and  suspended  beneath  this  is  the  operating  platform.  Power  is 
communicated  to  the  crane  by  an  endless  rope,  moving  continually 
in  one  direction,  and  driven  by  a  suitable  wheel  on  a  stationary 
shaft  at  one  end  of  the  longitudinal  tracks,  this  shaft  being 
driven  by  power  transmitted  in  any  convenient  manner  from  a 
stationary  engine,  either  directly  or  through  the  line  shafting. 
The  mechanism  of  the  crab  is  such  that  the  operator,  standing 
upon  the  suspended  platform,  is  enabled,  by  means  of  three  levers, 
to  apply  the  power  so  as  to  cause  the  bridge  to  travel  longitudi- 
nally on  the  tracks  in  either  direction,  or  the  trolley  to  travel  in 
either  direction  across  the  bridge,  or  to  raise  or  lower  the  load. 
The  bridge  and  trolley  may  be  moved  independently  or  simul- 
taneously, at  will. 

The  motions  of  the  bridge  are  effected  by  the  Weston  system 
of  fixed  wire  cables  as  explained  at  Part  II,  page  58.  These 


Power   Traveling  Cranes.  157 

cables  are  so  arranged  as  to  constitute  a  perfect  squaring  device, 
which  insures  the  absolute  parallelism  of  the  end  trucks  of  the 
bridge  with  their  tracks  under  all  conditions,  so  that  the  bridge 
always  moves  smoothly  and  with  the  least  possible  friction.  The 
motions  of  the  trolley  on  the  bridge  are  effected  through  the  two 
parts  of  the  main  hoisting  chain,  as  explained  at  Part  II,  page  65, 
thus  avoiding  the  need  of  an  independent  traversing  mechanism 
and  greatly  simplifying  the  machine. 

The  hoisting  and  lowering  gear  consists  of  cut  worm  wheels 
with  bronze  rims,  driven  by  cut  steel  worms  running  in  oil,  and 
provided  with  automatic  devices  by  which  the  load  is  always  self- 
sustained.  Motion  is  transmitted  to  the  worm  gears  by  cut  spur 
gearing,  driven  by  the  primary  shaft,  which  in  turn  is  driven  con- 
tinuously in  one  direction  by  the  driving  rope.  The  power  re- 
quired to  effect  the  several  motions  of  the  machine  is  taken  from 
the  primary  shaft  by  a  series  of  Weston-Capen  Frictional  Disc 
Clutches,  the  details  of  this  arrangement  being  described  in  Part 
II,  page  73  et  seq.,  and  the  clutches  at  page  41. 

Automatic  stops  are  provided  for  arresting  the  transverse 
motion  of  the  trolley  at  either  end  of  the  bridge,  and  of  the  bridge 
at  either  end  of  the  longitudinal  tracks,  so  that  over-travel,  either 
of  the  bridge  or  of  the  trolley,  cannot  by  any  accident  occur. 

Provision  is  always  made  for  two  speeds  of  hoisting  and  low- 
ering, and  when  desired  back  gearing  is  added  to  the  crab,  thus 
affording  four  speeds  of  hoisting  and  lowering  and  two  speeds  of 
travel,  both  of  bridge  and  trolley.  When  desired,  hand  gearing 
can  be  also  added  to  enable  the  -crane  to  be  moved  by  hand  in  the 
event  of  the  power  being  temporarily  disabled.  This  adds  some- 
what to  the  expense  of  the  crane  and  is  usually  not  desirable,  as 
the  motions  by  hand  are  necessarily  very  slow  and  the  occasions 
for  its  use  very  rare.  The  details  by  which  the  motions  are  ac- 
complished are  fully  described  in  Part  II  at  page  73. 

The  operating  -platform  should,  if  possible,  be  arranged  as 
shown  in  the  engraving,  beneath  the  bridge,  as  in  this  position 
the  operator  has  best  command  of  the  floor  below.  Where  the 
head  room  does  not  allow  of  this,  or  where  other  obstructions  in- 
terfere, the  platform  can  be  arranged  at  each  side  of  the  bridge 


158  A    Treatise  on  Cranes. 

and  projecting  but  slightly  below  the  crab.  But,  for  the  reason 
above  given,  this  arrangement  is  not  so  good  as  that  shown  in 
the  engraving.  A  foot  way  across  the  bridge  gives  access  to  the 
parts  attached  to  the  latter,  and  also  to  the  trolley.  The  main 
chain  sheaves  have  anti-friction  bushings  (see  Part  II,  page  95) 
and  the  action  is  such  as  to  distribute  the  wear  equally  throughout 
the  entire  length  of  the  chain  (see  page  67). 

The  power  traveling  crane  constitutes  the  most  perfect  and 
complete  apparatus  for  handling  heavy  loads,  and  is  to  be  pre- 
ferred to  all  other  types  of  cranes,  wherever  the  construction  of 
the  building  and  the  other  surrounding  conditions  admit  of  its 
use.  It  avoids  all  strains  other  than  vertical  upon  the  building 
in  which  it  is  contained,  and  for  its  support  requires  merely  a 
trestle  or  wall  of  sufficient  stability  to  resist  the  direct  pressure 
of  the  crane  and  its  load,  so  that  there  is  practically  no  limit  to 
the  capacity  which  may  be  obtained.  With  jib  cranes,  on  the 
contrary,  lateral  strains  upon  the  building  are  unavoidably  intro- 
duced ;  and,  where  the  crane  is  large,  either  in  capacity  or  di- 
mensions, these  strains  become  exceedingly  severe.  A  jib  crane 
encroaches  seriously  upon  the  floor  it  covers,  and  its  capacity  for 
the  horizontal  transfer  of  loads  is  necessarily  very  limited.  The 
traveling  crane,  on  the  contrary,  leaves  the  floor  below  it  entirely 
clear,  and  is  practically  unrestricted  in  the  length  of  its  travel. 
The  designing  of  the  Weston  Power  Traveling  Cranes  has  been 
a  subject  of  the  most  careful  study  and  thorough  experiment,  ex- 
tended over  a  number  of  years.  It  is  believed  that  these  are  the 
most  highly  organized  and  mechanically  perfect  cranes  which  have 
ever  been  built. 

Cranes  of  this  construction  are  adapted  for  use  in  machine 
shops,  forges,  boiler  shops,  rolling  mills,  stone  yards,  and  other 
places  where  heavy  loads  are  to  be  handled,  and  where  it  is  de- 
sired to  accomplish  this  in  the  most  efficient  and  economical  man- 
ner. Where  actively  employed  cranes  of  this  type  will  do  the  work 
of  from  20  to  50  men  using  the  ordinary  devices  of  tackles,  jacks 
and  screws,  so  that  it  is  demonstrable  in  many  cases  that  the 
economy  effected  by  a  crane  within  one  or  two  years  will  en- 
tirely cover  the  cost  of  procuring  it. 


Power   Traveling  Cranes. 


'59 


Estimates  for  power  traveling  cranes  will  be  furnished  upon 
receipt  of  information  giving  the  following  particulars,  viz.:  maxi- 
mum load  to  be  handled,  span  or  length  of  bridge,  length  of  lon- 
gitudinal travel,  height  from  floor  to  ceiling  or  roof,  and  such 
particulars  as  to  the  nature  of  the  work  to  be  done  as  will  enable 
the  builders  to  clearly  understand  it  and  to  arrange  the  crane 
accordingly. 


FIG.  64. — Power  Traveling  Crane,  as  applied -to  Foundry  Use. 


Power   Traveling  Cranes.  161 


POWER   TRAVELING-   CRANE. 


DOUBLE    TROLLEYS TWO   CRANES    ON    SAME    TRACKS. 


Fig.  65,  on  opposite  page,  represents  a  locomotive  repair  shop 
equipped  with  two  Weston  Power  Traveling  Cranes,  running  upon 
the  same  longitudinal  tracks,  and  each  crane  provided  with  two 
trolleys,  thus  giving  four  running  blocks  and  enabling  the  load  to 
be  suspended  from  four  points. 

The  cranes  used  for  this  purpose  are  indentical  with  those 
shown  and  described  on  pages  155  to  158,  to  which  reference  is 
made  for  particulars  as  to  their  construction.  The  arrangement 
of  the  cranes  herewith  represented  is  useful  in  many  situations. 
The  use  of  two  cranes  upon  the  same  set  of  overhead  tracks  is 
desirable  in  foundries,  for  handling  very  heavy  castings,  an'd  in 
large  shops  for  the  erection  of  machinery  and  for  similar  pur- 
poses. Two  separate  machines  are  thus  obtained,  each  available 
for  use  independently  of  the  other,  while  for  handling  very  heavy 
loads,  or  very  long  pieces  of  work,  the  two  cranes  can  be  brought 
together  and  both  used  simultaneously. 

The  arrangement  of  two  trolleys  upon  one  crane  is  less  fre- 
quently required,  but  is  desirable  for  such  work  as  is  represented 
in  Fig.  65,  as  it  distributes  the  strains  on  the  bridge  and  enables 
the  load  to  be  seized  at  several  points.  In  cranes  having  two 
trolleys  the  operating  levers  are  doubled,  thus  giving  the  operator 
control  of  each  trolley  independently  of  the  other.  The  addition 
of  a  second  trolley  is  effected  with  but  slight  increase  in  space 
occupied  by  the  operating  mechanism,  but  necessarily  adds  con- 
siderably to  the  expense  of  the  crane. 

As  shown  in  Fig.  65,  each  of  the  two  traveling  cranes  is  con- 
trolled by  a  separate  operator  standing  upon  its  platform,  who,  as 
above  explained,  is  enabled  to  control  independently  each  of  the 


)62  A   Treatise  on  Cranes. 

two  trolleys  upon  each  crane.  The  method  of  transmission  of 
power  assures  equal  speeds  upon  both  machines,  so  that  they 
may  be  combined,  as  shown  in  the  engraving,  and  their  united 
power  utilized  for  lifting  a  heavy  load  suspended  from  the  four 
blocks  or  tackles.  At  other  times  the  two  cranes  may  be  sep- 
arated, and  used  independently  in  different  parts  of  the  shop. 

Wherever  large  loads  are  to  be  occasionally  handled,  and 
particularly  where  these  loads  consist  of  long  pieces,  as  in  bridge 
work,  it  is  always  better  to  have  two  cranes,  whose  combined 
capacity  shall  furnish  the  maximum  power  required,  rather  than 
one  of  larger  size.  For  handling  heavy  loads  of  most  kinds, 
the  two  cranes  are  really  better  than  one,  while  at  other  times 
they  afford  the  convenience  of  two  distinct  machines,  each  of  which, 
being  smaller  and  lighter  than  a  crane  of  larger  capacity,  is 
better  adapted  for  handling  light  loads  and  performing  the 
ordinary  work  required  of  it.  Where  two  cranes  are  thus  com- 
bined it  is  not  necessary  that  their  capacity  should  be  equal. 
For  instance,  where  a  maximum  capacity  of  25  tons  is  required, 
it  is  often  found  best  to  construct  one  of  the  cranes  with  a  capac- 
ity of  15  tons  and  the  other  of  10  tons,  the  latter  being  used 
for  the  lighter  parts  of  the  work,  the  former  for  the  heavier,  and 
both  cranes  brought  together  when  the  maximum  capacity  is 
desired. 

Estimates  will  be  furnished  for  cranes  arranged  in  the 
manner  above  explained,  upon  receipt  of  the  same  information  as 
specified  upon  page  159. 


PART    IV. 


PART  IV. 


INTRODUCTION. 


In  designing  and  building  machinery  for  hoisting  and  trans- 
ferring light  loads,  many  of  the  same  problems  are  presented 
which  occur  in  the  construction  of  heavy  cranes,  and  the  experi- 
ence gained  in  one  is  available  in  the  other.  Too  much  has 
heretofore  been  left  to  "  rule  of  thumb  "  practice  in  the  designing 
of  light  hoisting  machinery,  and  frequent  accidents  to  life  and  limb 
still  needlessly  occur  from  continued  adherence  to  old  types  of 
machines  in  which  safety,  both  of  person  and  load,  depends  upon 
the  care  and  intelligence  of  the  operator. 

It  is  possible  to  so  construct  hand  hoisting  machinery  that 
accidents  arising  from  carelessness  in  its  use  are  practically  im- 
possible. Such  construction  involves  no  sacrifice  of  simplicity  or 
efficiency,  and  no  material  increase  in  cost.  To  adhere  to  the 
old,  therefore,  is  to  assume  needless  risks  to  property  and  un- 
justifiable risks  to  human  life.  The  risks  referred  to  arise  chiefly 
from  two  causes  ;  first,  a  deficiency  of  material  in  parts  subject  to 
strain  ;  and,  second,  the  use  of  ratchet  wheels  to  hold  the  load 
suspended,  and  of  non-automatic  brakes  to  effect  lowering.  The 
first  defect,  a  want  of  proper  kind  or  amount  of  material,  arises 
from  unskillful  designing  and  from  the  effort  after  cheapness. 
The  second  is  inherent  in  the  elements  of  mechanism  employed, 
and  can  only  be  avoided  by  the  use  of  new  and  better  devices,  so 
constructed  as  to  be  automatic  in  all  functions  where  carelessness 
is  potent  to  produce  harm. 

The  active  operation  of  hoisting  is  usually  free  from  danger 
in  any  machine  of  sufficient  strength.  It  is  the  descent  of  the 
load,  whether  by  intention  or  by  accident,  that  involves  danger. 
During  the  act  of  hoisting  the  operator  slowly  expends  power, 


1 66  A    Treatise  on  Cranes. 

which  is  stored  up  as  latent  energy  in  the  mass  he  has  raised,  and 
which,  if  expended  or  given  back  suddenly,  as  in  falling,  is  cap- 
able of  working  serious  mischief.  The  mechanism  should, 
therefore,  be  so  constructed  that  the  load,  when  lifted,  shall  be 
sustained  independently  of  the  operator,  so  that,  should  he 
cease  his  efforts,  or  even  suddenly  let  go  the  rope  or  handles,  the 
load  will  simply  cease  to  move  and  will  remain  suspended.  Un- 
der no  circumstances  should  the  load  be  permitted  to  descend  by 
gravity  unaided  by  the  controlling  hand  of  the  operator.  This 
principle  of  construction,  namely,  the  control  of  the  load,  at  all 
times  and  under  all  conditions,  by  reliable  automatic  devices,  is 
embodied  in  all  of  the  hoisting  appliances  described  in  the  follow- 
ing pages. 


Relation  of  Power  to  Speed.  167 


RELATION  OF  POWER  TO  SPEED. 


In  ordering  hoisting  machines,  customers  not  infrequently  ask 
for  "  great  power  "  and  "  quick  speed  "  in  the  same  machine.  That 
is,  they  call  for  a  machine  in  which  one  man  can  lift  a  very  heavy 
load  and  raise  it  quickly.  In  answer  to  such  demands,  the  follow- 
ing explanation  of  the  mechanical  facts  involved  is  submitted. 

Power  and  speed  are  convertible  terms.  A  man  may  with  one 
machine  lift  1,000  pounds  10  feet  high  in  one  minute,  and  with  an- 
other machine,  differently  geared,  may  lift  100  pounds  100  feet 
high,  in  one  minute.  In  each  case  the  work  accomplished  is  the 
same,  and  is  expressed  mechanically  by  multiplying  the  weight 
by  the  number  of  feet  it  is  lifted  in  one  minute,  the  result  being 
designated  "foot-pounds."  In  each  of  the  above  supposed  cases 
the  work  accomplished  amounts  to  10,000  foot-pounds. 

The  average  efficiency  of  a  man  working  on  a  crank  or  rope 
is  from  4,000  to  8,000  foot-pounds  per  minute  for  ordinary  work. 
These  figures  can  be  considerably  increased  during  short  periods. 

A  hoisting  machine  can  be  proportioned  with  any  ratio  of 
gearing  desired.  If  wanted  to  hoist  rapidly  it  means  that  one 
man  can  lift  only  a  small  load.  If  wanted  to  hoist  a  heavy  load 
it  follows  that  one  man  can  raise  that  load  only  very  slowly. 

The  ratio  of  gearing  in  the  various  hoisting  machines  herein 
illustrated  is  that  which  experience  has  demonstrated  to  be  the. 
best  and  most  convenient  for  ordinary  purposes.  It  is  always 
such  that  the  maximum  load  for  which  the  machine  is  intended 
can  be  raised  at  the  quickest  speed  which  is  possible  with  the 
number  of  men  employed.  When  desired,  the  ratio  of  the  gearing 
can  usually  (at  some  extra  expense)  be  varied,  but  it  must  be  re- 
membered that  any  gain  of  speed  is  always  accompanied  by  a 
corresponding  loss  of  power,  and  any  gain  of  power  accompanied 
by  a  corresponding  loss  of  speed.  It  is  not  posssible,  without  an 
increase  in  the  amount  of  power  applied  to  the  machine,  to  simul- 
taneously increase  both  its  power  and  speed. 


1 68  A    Treatise  on  Cranes. 


WESTON'S    DIFFERENTIAL     PULLEY 
BLOCK. 

The  portable  hoisting  device  generally  known  by  the  above 
name  was  invented  some  twenty  years  ago.  It  secured  immedi- 
ately great  popularity,  and  its  use  extended  rapidly  throughout 
the  civilized  world,  wherever  modern  machinery  was  known  and 
appliances  for  lifting  heavy  weights  were  needed.  No  previous 
device  had  ever  embodied  the  same  conveniences,  namely,  great 
lifting  power  and  the  ability  to  hold  the  load  suspended  at  any 
point,  and  the  accomplishment  of  these  ends  by  a  machine  of 
great  simplicity,  compactness,  and  of  light  weight.  The  univer- 
sal adoption,  throughout  the  world,  of  the  Weston  Differential 
Pulley  Block  as  the  standard  type  of  portable  hoists,  is  due  to 
the  fact  that  it  perfectly  meets  all  of  these  requirements  and  in 
the  simplest  possible  way.  Since  its  introduction  other  machines 
have  been  invented  for  similar  uses,  but  no  one  of  them  combines 
in  itself  the  important  characteristics  of  power,  safety,  simplicity 
and  portability  to  a  degree  which  equals  that  of  the  Weston 
Block.  The  latter  is  demonstrably  a  reduction  of  the  problem  to 
its  simplest  possible  form,  and  therefore  can  never  be  superseded. 
In  recent  text  books  it  is  given  a  place  among  the  other  mechan- 
ical powers  or  elements,  thus  recognizing  the  fundamental  char- 
acter of  its  design  and  usefulness. 

The  principles  on  which  the  action  of  the  differential  pulley 
block  is  based  are  not  generally  understood.  They  have  been 
clearly  discussed  by  Professor  Ball,  and  his  description  of  them 
is  reproduced  below. 

THE   DIFFERENTIAL    PULLEY    BLOCK.* 

The  principle  of  the  differential  pulley  is  very  ancient,  but  it 
is  only  recently  that  it  has  been  embodied  in  a  machine  of  prac- 

*  Experimental  Mechanics,  by  R.  S.  Ball,  A.M.,  Macmillan  &  Co.,  London,  1871  ;   page 
112  et  seg. 


The  Differential  Pulley  Block. 


169 


tical  utility.  In  designing  any  mechanical  power  the  object  to  be 
aimed  at  is  this,  that  while  the  power  moves  over  a  considerable 
distance  the  load  shall  only  be  raised  a  short  distance.  When  this 
object  is  attained  we  then  know  by  the  principle  of  energy  that  we 
have  gained  an  increase  of  power. 

Let  us  consider  the  means  by  which  this  is  effected  in  thatp 
ingenious  contrivance,  Weston's  Differential  Pulley  Block.     The 
principle  of  this  machine  will  be  understood  from  Fig.  66  and 
Fig.  67. 

It  consists  of  three  parts— an  up- 
per pulley  block,  a  movable  pulley, 
and  an  endless  chain.  We  shall 
briefly  describe  them.  The  upper 
block  P  is  furnished  with  a  hook  for 
attachment  to  a  support.  The  sheave 
it  contains  resembles  two  sheaves, 
one  a  little  smaller  than  the  other, 
fastened  together  ;  they  are  in  fact 
one  piece.  The  grooves  are  furnished 
with  ridges  which  prevent  the  chain 
from  slipping  around  them.  The 
lower  pulley  Q  consists  of  one  sheave 
'which  is  also  furnished  with  a  groove, 
it  carries  a  hook  to  which  the  load 
FIG.  66.  is  attached.  The  endless  chain  per- 

forms a  part  that  will  be  understood  by  the  arrow  heads  attached 
to  it  in  the  figure.  The  chain  passes  from  the  hand  at  A  up  to 
L,  over  the  larger  groove  in  the  upper  pulley,  then  downwards 
at  B,  under  the  lower  pulley,  up  again  at  C,  over  the  smaller 
groove  in  the  upper  pulley  at  M,  and  then  back  again  by  D  to  the 
hand  at  A.  When  the  hand  pulls  the  chain  downwards  the 
grooves  of  the  upper  pulley  begin  to  turn  together  in  the  direc- 
tion shown  by  the  arrows  on  the  chain.  The  large  groove  is 
therefore  winding  up  the  chain  while  the  smaller  is  lowering. 

In  the  pulley  which  has  been  employed  in  the  experiments 
to  be  described  the  effective  circumference  of  the  large  groove  is 
found  to  be  11.84  inches,  while  that  of  the  small  groove  is  10.36 


170  A  Treatise  on  Cranes. 

inches.  When  the  upper  pulley  has  made  one  revolution  the 
large  groove  must  have  drawn  up  11.84  inches  of  chain,  since  the 
chain  cannot  slip  on  account  of  the  ridges  ;  but  in  the  same  time 
the  small  groove  has  lowered  10.36  inches  of  chain  ;  hence,  when 
the  upper  pulley  has  revolved  once,  the  chain  between  the  two  must 
have  been  shortened  by  the  difference  between  11.84  and  10.36 
inches,  that  is,  by  1.48  inch  ;  but  this  can  only  have  taken  place 
by  raising  the  movable  pulley  through  half  1.48  inch,  that  is, 
through  a  space  of  .74  inch.  The  power  has  then  acted  through 
11.84  inches  and  has  raised  the  resistance  .74  inch.  The  power 
has  therefore  moved  through  a  space  16  times 
greater  than  that  through  which  the  load  moves. 
In  fact  it  is  very  easy  to  verify  by  actual  trial  that 
the  power  must  be  moved  through  16  feet  in  order 
that  the  load  may  be  raised  i  foot.  We  express 
this  by  saying  that  the  velocity  ratio  is  16. 

By  applying  power  to  the  chain  at  D,  proceed- 
ing from  the  smaller  groove,  the  chain  is  lowered 
by  the  large  groove  faster  than  it  is  raised  by  the 
small  one,  and  the  lower  pulley  descends.  The 
load  is  thus  raised  or  lowered  with  great  facility  by 
simply  pulling  one  chain  A  or  the  other  D. 

We  shall  next  consider  the  mechanical  efficiency 
of  the  differential  pulley  block.  The  block  (Fig. 
67)  which  we  shall  use  is  intended  to  be  worked  by 
one  man  and  will  raise  any  weight  not  exceeding 
a  quarter  of  a  ton. 

We  have  already  learned  that  for  the  load  to  be 
raised  i  foot  the  power  must  act  through  16  feet. 
Hence  were  it  not  for  friction  we  should  infer  that 
the  power  need  only  be  the  i6th  part  of  the  load. 
A  few  trials  will  show  us  that  the  real  efficiency  is 
not  so  large,  and  that  in  fact  more  than  half  the 
FIG.  67.        power  exerted  is  merely  expended  upon  overcoming 
friction.     This  will  lead  afterwards  to  a  result  of  considerable 
practical  importance. 

Placing  upon  the  load-hook  a  weight  of  200  pounds   I  find 


The  Differential  Pulley  Block. 


171 


that  38  pounds  attached  to  a  hook  fastened  on  the  power-chain 
is  sufficient  to  raise  the  load  ;  that  is  to  say,  the  power  is  about  -£• 
of  the  load.  If  I  make  the  load  400  pounds  I  find  the  requisite 
power  to  be  64  pounds,  which  is  only  about  3  pounds  less  than  •£ 
of  400  pounds.  We  may  safely  adopt  the  practical  rule  that  with 
a  differential  pulley  block  of  this  class  a  man  will  be  able  to  raise 
a  weight  six  times  greater  than  he  could  raise  without  such 
assistance. 

A  series  of  experiments  carefully  tried  with  different  loads 
have  given  the  results  shown  in  the  following  table  : 


THE   DIFFERENTIAL    PULLEY    BLOCK. 

Circumference  of  large  groove,  n"'84,  of  small  groove, 
io"'36  ;  velocity  ratio,  16  ;  mechanical  efficiency,  6-07  ;  useful 
effect  38  per  cent.;  formula  Pi=3'87  +  0*1508  R. 


Number  of 
Experiment. 

R. 

Load  in  pounds. 

Observed  power 
in  pounds. 

p. 

Calculated  power 
in  pounds. 

Difference  of  the 
observed  and 
calculated  values. 

I 

56 

10                    12-3 

+    2-3 

2 

112 

20                             20'8 

+  0-8 

3 

168 

3I                             29-2 

-  1-8 

4 

224 

38                  377 

-  o-3 

5 

280 

48                  46-1 

-  1-9 

6 

336 

54 

54'6 

+  0-6 

7 

392 

64 

63-1 

—  0-9 

8 

448 

72 

7i'5 

-  °'5 

9 

5°4 

80 

80-0 

O'O 

10 

560 

86 

88-4 

+  2-4 

The  first  column  contains  the  numbers  of  the  experiments  ; 
the  second  the  weights  raised  ;  the  third  the  values  of  the  cor- 
responding powers.  From  these  the  following  rule  for  finding 
the  power  has  been  obtained  : 

To  find  the  power  multiply  the  load  by  0.1508  and  add  3.87 
pounds  to  the  product ;  this  rule  may  be  expressed  by  the 
formula 

P  =  3.87  +  0.1508  R. 


172  A   Treatise  on  Cranes. 

The  calculated  values  of  the  powers  are  given  in  the  fourth 
column,  and  the  differences  between  the  observed  and  calculated 
values  in  the  last  column.  The  differences  do  not  in  any  case 
amount  to  2.5  pounds,  and  considering  the  size  of  the  loads  raised 
(up  to  a  quarter  of  a  ton),  the  formula  represents  the  experi- 
ments with  satisfactory  precision. 

Suppose,  for  example,  280  pounds  is  to  be  raised  ;  the 
product  of  280  and  0.1508  is  42.22,  to  which  when  3.87  is  added 
we  find  46.09  to  be  the  requisite  power.  The  mechanical  effic- 
iency found  by  dividing  46.09  into  280  is  6.07. 

To  raise  280  pounds  i  foot,  280  foot-pounds  of  energy  would 
be  necessary,  but  in  the  differential  pulley  block  46.09  pounds 
must  be  exerted  for  a  distance  of  16  feet  in  order  to  accomplish 
this  object.  The  product  of  46.09  and  16  is  737.4.  Hence,  the 
differential  pulley  block  requires  737.4  foot-pounds  of  energy  to 
be  applied  to  it  in  order  to  produce  280  foot-pounds  ;  but  280  is 
only  38  per  cent,  of  737.4,  and  therefore,  with  a  load  of  280 
pounds  only  38  per  cent,  of  the  energy  applied  to  a  differential 
pulley  block  is  utilized.  In  general  we  may  state  that  not  more 
than  about  40  per  cent,  is  profitably  used,  and  that  the  remainder 
is  employed  in  overcoming  friction. 

It  is  a  very  remarkable  and  useful  property  of  the  differen- 
tial pulley  that  a  weight  which  has  been  hoisted  by  it  will  remain 
suspended,  without  any  tendency  to  run  down  ;  this  is  a  point 
of  great  practical  convenience.  In  all  pulleys  we  have  previously 
considered  this  property  does  not  exist.  The  weight  raised  by 
the  3-sheave  pulley  block,  for  example,  will  run  down  unless  the 
free  end  of  the  rope  be  properly  secured.  The  differences  in  this 
respect  between  these  two  mechanical  powers  is  not  a  consequence 
of  any  special  mechanism  ;  it  is  simply  caused  by  the  excessive 
friction  in  the  differential  pulley  block. 

The  reason  why  the  load  does  not  run  down  in  the  differen- 
tial pulley  may  be  thus  explained.  Let  us  suppose  that  a 
weight  of  400  pounds  is  to  be  raised  i  foot  by  the  differential 
pulley  block  ;  400  units  of  work  are  necessary  and  therefore 
1,000  units  of  work  must  be  applied  to  the  power-chain  to  produce 
the  400  units  (since  only  40  per  cent,  is  utilized).  The  friction 


The  Differential  Pulley  Block.  i  73 

will  thus  have  consumed  600  units  of  work  when  the  load  has 
been  raised  i  foot.  If  the  power-weight  be  removed,  the  pressure 
supported  by  the  upper  pulley  block  is  diminished.  In  fact,  since 
the  power-weight  is  about  f  of  the  load  the  pressure  on  the  axle 
when  the  power-weight  has  been  removed  is  only  f  of  its  previous 
value.  The  friction  is  produced  by  the  pressure  of  the  pulleys 
on  their  axles  and  is  nearly  proportional  to  that  pressure  ;  hence 
when  the  power  has  been  removed,  the  friction  on  the  upper  axle 
is  f  of  its  previous  value,  while  the  friction  on  the  lower  pulley 
remains  unaltered. 

We  may,  therefore,  assume  that  the  total  friction  is  at  least 
f-  of  what  it  was  before  the  power-weight  was  removed. 
Will  friction  allow  the  load  to  descend  ?  600  foot-pounds  of 
work  were  required  to  overcome  the  friction  in  the  ascent :  at 
least  f  x  600  =  514  foot-pounds  would  be  necessary  to  overcome 
friction  in  the  descent.  But  where  is  this  energy  to  come  from  ? 
The  load  in  its  descent  could  only  yield  400  units,  and  thus  de- 
scent by  the  mere  weight  of  the  load  is  impossible.  To  enable 
the  load  to  descend,  we  have  actually  to  aid  the  movement  by 
pulling  the  chain  D  (Figs.  66  and  67),  which  proceeds  through 
the  small  groove  in  the  upper  pulley. 

The  principle  which  we  have  here  established  extends  to 
other  mechanical  powers  and  maybe  stated  generally.  Whenever 
rather  more  than  half  of  the  applied  energy  is  uselessly  consumed 
by  friction,  the  load  will  remain  suspended  without  overhauling. 


Professor  Ball  then  proceeds  to  consider  other  forms  of  self- 
sustaining  blocks  and  shows  that  they  also  consume  60  per  cent, 
of  energy  in  friction,  but  that  their  mechanical  efficiency  is  some- 
what less  than  that  of  the  Weston  Differential  Pulley  Block.  His 
statement  that  the  friction  in  the  differential  block  "  is  produced 
by  the  pressure  of  the  pulleys  on  their  axles,"  and  that  it  is  this 
friction  alone  which  sustains  the  load,  is  probably  incorrect.  The 
friction  of  the  other  parts,  particularly  of  the  links  of  the  chain 
upon  one  another  and  in  the  pockets  of  the  chain  wheels,  is  un- 
doubtedly an  important  factor.  Indeed  the  mere  axle  friction  is 


174  A    Treatise  on  Cranes. 

not  much  greater  in  the  differential  block  than  in  the  common  rope 
block  and  obviously  would  not  alone  sustain  the  load.  His  other 
deductions,  however,  are  based  upon  actual  and  careful  experi- 
ment, and  are  doubtless  correct. 

The  important  fact  which  they  demonstrate  is  that  any  ma- 
chine of  this  type  which  automatically  sustains  the  load  by  the 
simple  friction  of  its  parts,  and  without  the  application  of  a  brake, 
can  only  have  a  mechanical  efficiency  of  something  less  than  50 
per  cent.  The  mechanical  efficiency  of  any  kind  of  hoisting 
machine  is  probably  not  more  than  80  to  90  per  cent,  of  the  ap- 
plied power.  The  difference  between  this  and  the  efficiency  of  a 
self-sustaining  hoist  -(which  is  about  40  per  cent,  of  the  applied 
power)  is,  in  the  latter  case,  absorbed  in  the  machine  itself  in 
order  to  impart  to  the  latter  the  capacity  of  holding  the  load 
always  self-sustained,  so  that  it  cannot  run  down,  and  so  that  the 
application  of  moderate  power  is  necessary  to  effect  lowering. 
The  differential  pulley  block,  particularly  in  its  geared  form, 
accomplishes  these  results  as  economically  as  is  practicable,  and 
possesses  greater  simplicity,  compactness  and  durability  than  any 
other  machine  of  this  type. 


WESTON'S 
SAFETY   HAND-HOISTING   MACHINERY. 

The  following  pages  contain  illustrations  of  a  variety  of 
hand-hoisting  appliances,  all  of  which  are  so  constructed  that  the 
load  is  always  self-sustained  and  cannot  run  down,  thus  guarding 
perfectly  against  accidents,  either  to  the  load  or  to  the  operator. 
They  are  all  of  them  essentially  "  safety  "  appliances. 

The  construction  of  the  differential  pulley  block,  and  the 
principle  on  which  its  self-sustaining  feature  is  based,  is  fully 
explained  in  the  preceding  article.  The  action  of  the  "double 
lift "  hoist  is  explained  in  Part  II,  page  34.  The  safety  hoist 
crab  and  winch,  each  contains,  in  one  form  or  another,  a  frictional 
safety  ratchet,  the  principle  of  which  is  explained  in  Part  II, 
Pa£e  33-  .The  general  construction  and  mode  of  action  of  each 
of  the  several  machines  is  described  in  connection  with  its 
illustration. 


76 


A   Treatise  on  Cranes. 


WESTON'S  "DIRECT" 

DIFFERENTIAL 
PULLEY    BLOCK  S. 


One  man  can  lift  1,000  Ibs. 
They  hold  the  load  at  any  point,  and 

cannot  run  down. 

Lifting  and  Lowering  effected  by  pulling 
opposite  sides  of  the  slack  chain. 


SIZES    OF    DIRECT    BLOCKS. 


Capacity. 

Regular 
Length  of 
Chain. 

Hoist. 
See  note.* 

Net  Weight. 
Complete. 

y&  Ton. 

l8ft. 

5     ft. 

ii  Ibs. 

X    " 

22     " 

6      " 

22       « 

%    " 

26     " 

7      " 

30       « 

i  " 

30     - 

8      « 

51       " 

i%  " 

33    " 

8^  « 

81     " 

2             " 

36    « 

9      " 

122       " 

3        " 

38    « 

9%" 

173        " 

FIG.  68.— "Direct"  Block. 


*NOTE — Figures  in  third  column  denote  approximate 
height  which  blocks,  with  regular  lengths  of  chain,  will 
hoist  from  level  on  which  operator  stands.  For  greater 
length  of  hoist  allow  about  four  feet  additional  of  chain 
for  each  foot  of  extra  hoist. 


These  are  the  most  simple  and  com- 
pact blocks  ever  devised,  and  are  recog- 
nized all  over  the  world  as  the  stand- 
ard type  of  portable  hand-hoisting 
machine.  They  are  a  finality,  for  the 
reason  that  they  solve  the  problem  with 
what  is  demonstrably  the  fewest  possible 
number  of  parts  and  the  greatest  possible 
simplicity,  both  of  form  and  action. 


Westoris  Differential  Pulley  Blocks.         177 


WESTON'S    "GEARED" 

DIFFERENTIAL 
P  U  L  LEY    BLOC K  S  . 

One  man  can  lift  from  2,000  to  5,000  Ibs. 

They  hold  the  load  at  any  point,  and  cannot 
run  down. 

Easy  and   smooth   in   action — compact   and 
convenient  to  handle. 


SIZES    OF    GEARED    BLOCKS. 


Regular  Lengths  of 
Main  Chain. 

Hoist. 

Net  Weight. 

Capacity. 

See  Note.* 

Complete. 

Main 

Hand 

Chain. 

Chain. 

i  Ton. 

22ft. 

1  6  ft. 

8ft. 

62lbs. 

2          " 

24    " 

18  « 

9    " 

109  " 

3      " 

26    " 

20    " 

10    " 

'59  " 

4       " 

28    " 

22    " 

II    " 

257  " 

5       " 

30    « 

24    " 

12    " 

324  " 

6      " 

32    " 

26    " 

13    " 

493  " 

8      " 

36    «« 

28    " 

I4    « 

735  " 

10         " 

40    " 

30    " 

16  " 

1054  " 

*NoTE.— Figures  in  fourth  column  denote  approximate  height 
which  Blocks,  with  regular  lengths  of  chain,  will  hoist  from  level 
on  which  operator  stands.  For  greater  length  of  hoist,  allow  2^ 
feet  of  Main  Chain,  and  2  feet  of  Hand  Chain  for  each  foot  of 
extra  hoist. 

These  blocks  have  all  the  merits  of  the 
"Direct"  blocks  shown  on  the  preceding 
page,  with  the  addition  of  a  small  train  of 
spur  gearing,  driven  by  a  separate  hand  chain, 
thus  affording  two  powers,  or  changes  of 
speed,  and  greatly  increasing  the  lifting  power 
of  the  operator.  The  action  is  smoother  than 
that  of  the  direct  block,  and  the  length  of 
the  hand  chain  does  not  vary. 


JBH 


FIG.  69.—"  Geared"  Block. 


A    Treatise  on  Cranes. 


WESTON'S 
SAFETY  "DOUBLE  LIFT"   HOISTS. 


FIG.  70.— Direct  "  Double  Lift "  Hoist. 

This  simple  and  convenient  little  machine  is  intended  espe- 
cially for  use  over  hatchways  and  in  similar  places,  and  "is  made 
in  capacities  from  500  to  2,000  pounds.  Fig.  70  shows  the  small- 
est size,  which  is  without  gearing.  The  larger  sizes  are  geared, 
as  shown  in  Fig.  71.  It  is  also  made  in  its  smallest  size,  in  port- 
able form  and  has  a  quicker  action  than  the  differential  block. 

The  "  Double  Lift "  consists  of  a  chain,  with  a  hook  on  each 
end,  passing  over  a  sheave  which  can  be  rotated  by  the  hand 
rope  and  wheel.  Pulling  one  side  of  the  rope  causes  the  opposite 
side  of  the  chain  to  rise  with  the  load.  Pulling  the  other  side  of 
the  rope  causes  the  load  to  descend,  but  only  as  fast  and  as  long 
as  the  rope  is  pulled.  If  the  rope  is  let  go  the  load  will  remain 
suspended  ;  it  can  never  run  down.  As  one  hook  ascends  the 
other  descends  and  is  thus  ready  for  the  next  load. 


Westoris  Safety  "Double  Lift"  Hoists.       179 


FIG.  71. — Geared  "Double  Lift"  Hoist. 

This  is  a  better,  safer  and  simpler  machine  than  the  old 
"  rope  wheel  and  drum  "  so  commonly 
used.  The  construction  of  its  parts 
by  which  the  self-sustaining  action  is 
obtained  is  described  in  Part  II,  page 
33,  to  which  reference  is  made  for  fur- 
ther particulars. 

Fig.  72  shows  the  "  Double  Lift "  as 
used    over  a  hatchway,  with    its   shaft 
extended  so  as  to  bring  the  rope  wheel 
beyond  the  line  of   the   opening.      Its 
application  to  light  cranes  is  shown  on  page  186. 


i8o 


A    Treatise  on  Cranes. 


WESTON'S  "SAFETY   HOIST." 


FIG.  73. — "Safety  Hoist." 

The  "  Safety  Hoist "  consists  of  an  ordinary  barrel  or  drum, 
on  which  the  hoisting  rope  or  chain  is  wound,  and  a  grooved  wheel 
for  the  hand  rope,  the  purchase  or  power  being  obtained  by  the 
difference  in  diameter  of  the  wheel  and  barrel. 

The  safety  device  consists  of  a  friction  ratchet  similar  to  that 
shown  in  Fig.  5,  page  36,  but  without  any  friction  discs.  Its  effect 
is  to  hold  the  load  always  self- sustained.  Lowering  is  effected  by 
pulling  the  hand  rope  in  the  contrary  direction  to  that  for  hoist- 
ing, and  is  made  rapid  by  imparting  due  velocity  to  the  fly  wheel ; 
but  as  the  fly  wheel  loses  its  momentum  and  comes  to  rest  so  also 
does  the  load  ;  the  self-sustaining  feature  being  constant  in  action 
and  inseparable  from  the  construction. 

This  machine  is  made  of  capacities  of  from  250  to  400  pounds, 
and  with  various  lengths  of  barrels,  according  to  the  height  of 
hoist. 


Westoris  "Safety  Hoists"  181 


WESTON'S  "SAFETY  HOIST," 

WITH    "  GOVERNOR  "    ACTION. 


FIG.  74. — Governor  Hoist. 

This  machine  is  identical  with  one  previously  described,  ex- 
cept that  it  has  added  a  "  governor  "  for  controlling  the  speed  of 
the  load  when  lowering,  so  that  the  load  is  allowed  to  descend 
by  gravity,  under  the  control  of  the  governor,  and  without 
assistance  from  the  operator 

Where  much  lowering  of  goods  is  necessary,  it  saves  the,  time 
of  one  man  and  often  enables  a  boy  to  be  substituted.  The 
load,  once  started  downward,  takes  care  of  itself  while  the 
operator  gets  his  next  load  ready.  The  governor  attached  to  the 


1 82  A  Treatise  on  Cranes. 

rope-wheel  automatically  controls  the  speed  of  descent,  whether 
the  load  be  light  or  heavy,  and  the  construction  is  such  that  the 
desired  rate  of  speed  may  be  easily  varied  by  the  adjustment  of  a 
screw. 

The  illustration  shows  the  governor  as  applied  to  a  Weston 
"  Safety  Hoist."  It  is  also  capable  of  attachment  to  shafts  of  any 
kind  for  the  purpose  of  governing  their  speed  and  guarding 
against  excessive  velocities. 


Westons  Hoisting  Crabs. 


183 


WESTON'S   HOISTING  CRAB, 


WITH    AUTOMATIC    SAFETY    BRAKE. 


FIG.  75.— Safety  Crab. 

The  crabs  and  winches  illustrated  on  this  and  the  succeeding 
page,  consist  of  the  usual  winding  barrel,  for  common  rope  or 
chain,  driven  by  manual  power,  applied  to  cranks,  through  two  or 
more  spur  wheels,  the  ratio  of  the  gearing  being  varied  in  the 
several  sizes  of  machines,  according  to  the  load  to  be  lifted. 

The  lifting  is  accomplished  in  the  usual  manner.  The 
lowering  is  done  with  the  least  possible  exertion,  by  winding 
the  handles  backwards,  and  as  long  as  this  motion  is  continued 
the  load  will  descend.  The  safety  ratchet  or  brake  is  of  the 
type  illustrated  by  Fig.  5,  page  36,  and  its  construction  such  that 
the  load  is  always  self-sustained  and  cannot  run  down.  The 


1 84 


A    Treatise  on  Cranes. 


WESTON'S   DERRICK  WINCH, 

WITH    AUTOMATIC    SAFETY    BRAKE. 


FIG.  76.— Safety  Winch. 

handles  cannot  recoil  on  the  operator,  and  if  suddenly  "let  go" 
at  any  time,  either  in  hoisting  or  lowering,  the  load  will  quietly 
come  to  rest  and  remain  suspended. 

The  smaller  size  has  only  a  single  speed  or  power ;  the 
larger  size,  two  changes  of  speed.  The  capacity  of  either  may  be 
increased  by  the  use  of  a  running  block  in  the  usual  manner. 


Westoris  Dredging   Winches. 


WESTON'S  DREDGINGWINCH, 

FOR    OYSTER    BOATS,  YAWLS,  ETC. 


FIG.  77.— Safety  (.Slip)  Winch. 

This  is  a  small  winch,  for  hauling  in  a  light  rope  or  chain, 
provided  with  a  friction  brake  or  clutch  so  adjusted  that  if  the 
strain  on  the  rope  exceeds  a  certain  limit,  the  brake  will  slip  and 
permit  the  rope  to  pay  out  by  unwinding  the  barrel. 

In  dredging,  the  clutch  is  set  so  as  to  give  a  pull  sufficient  to 
lift  the  usual  load,  but  to  slip  if  this  load  is  exceeded,  so  that,  by 
means  of  this  slipping,  the  bow  of  the  boat  is  free  to  rise  to  the 
seas,  even  if  the  grapple  has  seized  too  large  a  load,  or  is  foul  of 
the  bottom.  The  operator  can  thus  safely  retain  his  hold  of  the 
cranks,  even  in  the  roughest  water,  without  danger  of  injury  to 
himself  or  of  swamping  his  boat. 


i86 


A  Treatise  on  Cranes. 


LIGHT   SWING   CRANE, 
WITH  WESTON'S   "  DOUBLE  LIFT  "  HOISTING  GEAR. 


FIG.  78.— Light  Swing  Crane. 

This  crane  consists  of  a  neat  wooden  frame,  turning  in  iron 
bearings  at  top  and  bottom,  and  provided  with  a  hoisting  gear 
consisting  of  a  double  lift,  as  described  on  page  178.  It  is  built 
of  capacities  from  500  pounds  to  2,000  pounds,  and  is  a  simple, 
safe  and  convenient  machine  for  light  work. 


Overhead  Tramrails. 


187 


OVERHEAD   TRAMRAILS. 


SINGLE    RAIL. 


FIG.  79. — Single  Tramrail. 

Fig.  79  represents  an  employment  of  the  differential  pulley 
block,  in  combination  with  an  overhead  rail  and  a  trolley,  which 
is  applicable  to  a  wide  range  of  uses,  and  by  which  at  slight  cost 
great  economy  can  be  effected  in  the  handling  of  moderate 
weights  of  all  kinds. 

The    track    employed    for   this    purpose  consists    of  light 


i88 


A   Treatise  on  Cranes. 


I-beams,  which  can  be  easily  curved  and  for  which  special 
forms  of  hangers,  fish-plates,  bolts,  etc.,  have  been  designed,  and 
which  are  also  provided,  where  necessary,  with  switches  and  turn- 
tables. 

The  trolley  is  arranged  to  run  freely  on  the  lower  flange  of 
the  tracks,  and  is  provided  with  four  wheels  or  rollers,  two  on 
each  side.  The  axles  of  these  wheels  are  inclined  at  such  an 
angle  that  the  bearing  of  the  wheels  coincides  with  the  angle  of 
the  flange  of  the  I-beam,  so  that  the  wheels  roll  easily  on  the 
latter  without  wear  or  undue  friction. 


FIG.  80. 


Patent  Trolley. 


FIG.  8 1. 


Fig.  80  is  a  side  elevation  and  Fig.  81  is  and  end  view  of  an 
overhead  tramrail  and  trolley,  showing  clearly  the  arrangement 
of  the  several  parts.  The  construction  of  the  fish-plates,  hangers, 
etc.,  is  such  that  they  avoid  all  interference  with  the  passage  of 
the  trolley,  and  thus  permit  the  track  to  be  extended  to  any 
desired  length,  while  by  means  of  switches  and  turn-tables  it  can 
be  carried  to  any  desired  points  within  a  building  or  yard,  and 
be  made  to  cover  the  entire  area  of  a  warehouse  or  works.  In 
short  lengths,  tracks  of  this  kind  are  particularly  useful  over 
large  lathes,  planers  and  other  machine  tools  to  assist  the  work- 
men in  handling  heavy  pieces  of  work. 


Overhead  Tramrails. 


189 


These  tramrails  are  built 
of  capacities  for  handling 
loads  of  all  sizes.  The  usual 
capacities  are  from  500  to 
2.000  pounds,  but  they  have 
been  built  of  sizes  to  handle 
loads  up  to  10  tons.  They 
are  applicable  to  a  wide 
range  of  uses,  the  precise 
construction  and  arrange- 


FIG.  82. — Single  Tramrail,  with  Switch. 

ment  varying  greatly  according  to  the  work  to  be  done. 


190 


A    Treatise  on  Cranes. 


OVERHEAD  TRAMRAILS. 


COMPOUND    RAILS. 


FIG.  83. — Compound  Tramrail. 

Fig.  83  represents  another  application  of  the  system  of  over- 
head tramrails  or  transfer  tracks.  The  arrangement  shown  in 
Figs.  79  and  82  admits  of  motion  in  one  direction  only,  that  is 
longitudinally  upon  the  rail. 

The  arrangement  shown  in  Fig.  83,  on  the  contrary,  consists 
of  two  parallel  rails,  supported  from  above,  with  a  light  bridge  or 


Overhead  Tramrails.  191 

traveler  running  upon  them,  and  this  in  turn  provided  with  a  trol- 
ley, so  that  the  bridge  can  be  moved  longitudinally  upon  the  rails, 
and  the  trolley  be  moved  transversely  on  the  bridge.  By  means  of 
the  compound  motion  thus  obtained  the  entire  space  included  be- 
tween the  two  overhead  tracks  can  be  reached. 

Fig.  83  shows  this  system  as  applied  to  a  warehouse  or  pack- 
ing room,  and  represents  four  pairs  of  overhead  tracks,  each  carry- 
ing an  independent  bridge,  so  that  the  entire  floor  of  the  ware- 
house is  covered  by  the  apparatus.  In  this  case  the  hoisting 
appliance  consists  of  a  portable  "Double  Lift"  (see  page  178) 
attached  directly  to  the  trolley,  which  moves  on  the  bridge.  This 
form  of  hoist  is  the  best  where  the  loads  to  be  handled  do  not 
exceed  500  Ibs.  For  larger  loads  the  differential  pulley  block 
constitutes  the  best  device.  Special  designs  of  hangers,  bridges, 
trucks  and  trolleys  have  been  devised  in  the  development  of  this 
system  of  handling  merchandize,  the  details  of  which  need  not  be 
here  described.  The  system  has  already  been  extensively  adopted 
with  most  satisfactory  results,  the  economy  resulting  from  its  use 
in  some  cases  defraying  the  cost  of  erection  within  the  first  year 
or  two. 


THE  Y 


ALE 

MANUFACTURERS,  ENGINEERS  and  MACHINISTS, 


Rfrij.  Go. 


Principal  Office  and  Works,  Stamford,  Conn. 


HENRY    R.   TOWNE,   President. 

•SCHTJYLER  MERRITT,  Secretary.  GEORGE  E.  WHITE,  Treasurer. 

TVM.  T.  PAYNE,  Ass't  Secretary.  THOS.  F.  KEATING,  Ass't  Treasurer. 

R,  CARTWRIGHT.  Gen'l  Superintendent  j 
R.  C.  CORNELIUS,  Business  Manager       f  ° 


O  "W  1ST I  N"  G- 

THE  YALE  LOCK  MFG.  CO. 

W.  H.  TAYLOR  &  E.  STOCKWELL,  Superintendents. 

THE  EMERY  SCALE  CO.  THE  WESTON  CRANE  CO. 

A.  H.  EMERY,  Vice  Pres.  &  Eng'r.  T.  W.  CAPEN,  Mech.  Eng'r. 


BRANCH  OFFICES. 

NEW  YORK  OFFICE, 62  READE  STREET. 

THOS.  F.  KEATING,  Manager. 

BOSTON  OFFICE,      .....        224  FRANKLIN  STREET. 

A.  T.  YOUNG,  Manager. 

PHILADELPHIA  OFFICE,        .  507  MARKET  STREET, 

MERLE  MIDDLETON,  Manager. 

WESTERN  OFFICE,  |  04 

WM.  F.  DONOVAN,  Manager. 


CHANGE  OF  CORPORATE  NAME. 


The  stockholders  of  the  Corporation  heretofore  known  as  THE 
YALE  LOCK  MANUFACTURING  COMPANY,  at  their  annual  meeting 
held  April  19th,  1883,  voted  to  accept  the  authority  given  them 
by  an  act  of  the  Legislature  of  Connecticut,  to  change  the  title  of 
the  Corporation  to  THE  YALE  &  TOWNE  MANUFACTURING  COMPANY^ 
by  which  latter  name  it  will  hereafter  be  known. 

The  change  is  one  of  name  only,  and  affects  neither  the  property 
and  franchises,  nor  the  obligations  of  the  Company.  It  has  become 
desirable  by  reason  of  the  greatly  enlarged  scope  of  the  Company's 
business,  in  which  the  manufacture  of  LOCKS,  under  the  Patents  of 
LINUS  YALE,  JR.,  and  others,  is  now  only  one  of  several  large 
departments,  the  tendency  of  the  old  name  being  to  mislead  custo- 
mers as  to  the  scope  of  the  business  and  the  facilities  of  the  Company 
for  its  transaction. 

During  the  past  seven  years  the  Company  has  gradually  built 
up  a  large  business  in  HOISTING  MACHINERY,  under  the  Patents  of 
THOS.  A.  WESTON  and  others,  including  CRANES  of  all  kinds  and  of 
the  largest  sizes,  and  has  recently  also  undertaken  the  manufacture 
of  the  "  EMERY  "  TESTING  MACHINES.  The  production  of  work  of 
this  class  involves  the  use  of  large  and  heavy  machinery,  and  con- 
stitutes a  branch  of  work  entirely  distinct  from  that  included  in  the 
Company's  Lock  and  Hardware  Department.  Another  department 
has  been  organized  for  the  manufacture,  under  the  Patents  of  A.  H. 
Emery,  of  SCALES  of  all  kinds,  and  of  PRESSURE  GAUGES,  the  devel- 
opment of  which  will  in  time,  it  is  believed,  make  this  department 
of  at  least  equal  importance  with  the  older  ones. 

It  will  thus  be  seen  that  the  business  of  the  Company  embraces 
not  only  the  manufacturing  operations  contemplated  under  its 
original  organization,  but  also  several  important  lines  of  heavy 
engineering  work.  The  buildings,  machinery  and  appliances  for  the 
latter  are  already  provided  and  in  full  operation,  and  the  change  of 
name  above  announced  is  chiefly  to  avoid  the  misunderstanding,  as 
to  the  Company's  business  and  facilities,  which  experience  has 
shown  to  result  from  the  limiting  word  "  LOCK,"  in  the  old  title. 
The  ownership  and  management  of  the  Company  remain  unchanged. 


For  reasons  not  necessary  to  enumerate,  it  has  been  found 
expedient  to  effect  a  subordinate  organization,  under  the  general 
laws  of  the  State,  bearing  the  old  title  of  THE  YALE  LOCK  MANI 
FACTURING  COMPANY,  and  also  a  similar  organization  entitled  THE 
WESTON  CRANE  COMPANY.  In  like  manner  THE  EMERY  SCALE 
COMPANY  was  organized  in  1882.  The  stock  of  all  of  these  subor- 
dinate companies  is  owned  and  controlled  by  the  parent  company, 
now  known  as  THE  YALE  &  TOWNE  MANUFACTURING  COMPANY, 
and  although  the  several  subordinate  organizations  will  be  per- 
manently maintained,  for  purposes  relating  to  the  ownership  of 
patents  and  other  franchises,  the  business  of  all  will  be  conducted 
by  THE  YALE  &  TOWNE  MANUFACTURING  COMPANY,  in  its  own 
name  and  for  its  own  account,  so  that  all  communications  should  be 
addressed  to  the  latter  name. 


CATALOGUES. 

THE  WESTON  CRANE  COMPANY'S  products  are  presented  in  this 
book.  Prices  on  application. 

THE  YALE  LOCK  MANUFACTURING  COMPANY'S  numerous  products 
are  embraced  in  the  following  several  catalogues,  each  devoted  to  a 
distinct  specialty,  any  of  which  will  be  sent  on  application,  viz. : 

A.— The  "  Yale  "  and  "  Standard  "  Locks. 

B. — Post  Office  Equipments. 

C. — Prison  and  Asylum  Locks. 

D. — Time  Locks. 

E. — Combination  Bank  Locks. 

THE  EMERY  SCALE  COMPANY'S  products  will  be  presented  by 
catalogue  as  rapidly  as  they  are  placed  on  the  market.  Orders  can 
now  be  executed  for  "  EMERY"  Testing  Machines,  full  information 
concerning  which  will  be  given  on  application. 


WORKS  OF  THE  YALE  &  TOWNE  MANUFACTURING  Co., 

ESTABLISHED,  1851.  INCORPORATED,  1868. 

STAMFORD,     CONN. 


The  Works  of  the  Yale  &  Towne  Manufacturing  Company,  which 
are  illustrated  in  the  above  engraving,  are  located  at  Stamford, 
Connecticut,  on  the  line  of  the  New  York,  New  Haven  &  Hartford 
Railroad,  thirty-four  miles  from  New  York.  Thirty-eight  trains 
pass  daily  in  each  direction  between  the  two  points,  the  express 
trains  making  the  run  in  fifty  minutes,  so  that  a  visit  from  New 
York  and  return  can  be  accomplished  in  a  few  hours. 

The  numerous  buildings  are  constructed  entirely  of  brick,  and 
are  exclusively  devoted  to  the  Company's  business.  The  general 
offices,  drafting  room,  etc.,  are  located  in  the  front  corner  building, 
which  is  in  great  part  fireproof.  The  other  buildings  include  the 
brass  and  iron  foundries,  forges,  chain  shop,  pattern  and  wood  work- 
ing shops,  machine  shops  for  various  kinds  of  work,  and  numerous 
rooms  devoted  to  light  manufacturing.  Kailroad  tracks  run  through 
the  yard  and  connect  with  the  railroad  system  of  the  country,  while 
water  communication  is  also  obtained  at  the  point  indicated  in  the 
background.  The  works  give  employment  to  about  700  operatives. 


UNIVERSITY  OF  CALIFORNIA 

DAVIS 
iiKirATALOGED 


LIST  OF  USERS  OF  THE  WESTON  CRANES, 


SOLE   MAKERS: 


THE  YALE  &  TOWNE  MFG.  CO., 


West  Quincy,  Mass. 
Pittsburgh,  Pa. 
Chicago,  111. 
St.  Louis,  Mo. 
Chicago,  111. 

Pittsburgh,  Pa. 
Troy,  N.  Y. 

Washington,  D.  C. 
Norfolk,  Va. 
Erie,  Pa. 
Providence,  R.  I. 
Holyoke,  Mass. 
Youngstown,  O. 
Elizabethport,  N.  J. 

Middletown,  N.  Y. 
Boston,  Mass. 

Chicago,  111. 
Hartford,  Conn. 
Torrington,  Conn. 
Providence,  R.  I. 

New  Orleans,  La. 
Joliet,  111. 
Bristol,  R.  I, 
Philadelphia,  Pa. 
Philadelphia,  Pa. 


F.  J.  FULLER, 

ATWOOD  &  MCCAFFREY, 

CHICAGO  FOUNDRY  Co., 

ST.  Louis  CAR  WHEEL  Co., 

UNION  IRON  AND  STEEL  MILL  Co., 

PITTSBURGH,  CINCINNATI  &  ST.  Louis 

RAILROAD  Co.,         .... 
ALBANY     &     RENSSELAER     IRON     AND 

STEEL  Co., 

U.    S.    ENGINEERS    FOR    WASHINGTON 

MONUMENT, 

U.  S.  NAVY  YARD,         .... 
ERIE  CITY  IRON  WORKS, 
WILLIAM  A.  HARRIS,      .... 
GEORGE  W.  PRENTISS  &  Co., 

WlLLIAfM    TOD    &    CO.,       . 

SINGER  MFG.  Co.,  .... 

NEW  YORK,  ONTARIO  &  WESTERN  RAIL- 
ROAD Co., 

NEW  YORK  &  NEW  ENGLAND  RAIL- 
ROAD Co.,  ..... 

CHICAGO,  BURLINGTON  &  QUINCY  RAIL- 
ROAD Co.,  ..... 

PRATT  &  WHITNEY  Co., 

TURNER  &  SEYMOUR  MFG.  Co., 

STAR  TOOL  Co., 

MORGAN'S  LOUISIANA  &  TEXAS  RAIL- 
ROAD,   

JOLIET  STEEL  Co., 

NATIONAL  RUBBER  Co., 

WILLIAM  SELLERS  &  Co., 

SCHLEICHER,   SCHUMM    &    Co., 


HARTFORD  ENGINEERING  Co., 
WESTINGHOUSE  MACHINE  Co., 
THE  EXCELSIOR  IRON  WORKS, 
WESTERN  MARYLAND  RAILROAD  Co.,    . 
BUILDERS'  IRON  FOUNDRY,    . 
CARNEGIE  BROS.  &  Co.,  (LIMITED), 
ATCHISON,  TOPEKA  &  SANTA  FE  RAIL- 
ROAD Co.,         . 

TANNER  &  DELANEY  ENGINE  Co., 
ROANOKE  MACHINE  WORKS, 
SCRANTON  STEEL  Co.,   . 


Hartford,  Conn. 
Pittsburgh,  Pa. 
Chicago,  111. 
Baltimore,  Md. 
Providence,  R.  I. 
Pittsburgh,  Pa. 

Topeka,  Kas. 
Richmond,  Va. 
Roanoke,  Va. 
Scranton,  Pa. 


MACKINSTOSH,  HEMPHILL  &  Co.,  (LIMITED),  Pittsburgh,  Pa. 


T.  F.  ROWLAND, 

ALLEGHENY  VALLEY   RAILROAD  Co.,     . 
MILLER,  METCALF  &  PARKIN, 
AMERICAN  DREDGING  Co.,     . 
WILLAMET  IRON  WORKS, 
BETTS  MACHINE  Co.,     . 
NORTHWESTERN  MFG.  £  CAR  Co., 
KIRKLAND  IRON  Co.,     . 
CHICAGO  &  ALTON  RAILROAD  Co., 
CHAPMAN  VALVE  MFG.  Co., 
AMERICAN  SHIP  BUILDING  Co., 
BALDWIN  LOCOMOTIVE  WORKS, 
BRIDESBURG  MFG.  Co.,  . 
WOOD,  TABER  &  .MORSE,       ..        .  *       : 
ELECTRO  METAL  REFINING  Co.,  . 
HENDEY  MACHINE  Co.,  ,     V.      ."**  '    - 
DENVER  £  Rio  GRANDE  RAILROAD  Co., 
THE  H.  B.  SMITH  Co., 
CALUMET  &  HECLA  MINING  Co., 
LEHIGH  VALLEY  RAILROAD  Co.,  . 
EDGE  MOOR  IRON  Co., 

P.  S.  REEVES, 

THE  CUMMER  ENGINE  Co.,    . 
AMERICAN  NAIL  MACHINE  Co.,     . 
NORTH  BROOKLYN  IRON  FOUNDRY  Co., 
CLEVELAND  CITY  FORGE  AND  IRON  Co., 
SERGEANT  &  CULLINGWORTH  Co., 


Brooklyn,  N.  Y. 
Pittsburgh,  Pa. 
Pittsburgh,  Pa. 
Philadelphia,  Pa. 
Portland,  Oregon. 
Wilmington,  Del. 
Stillwater,  Minn. 
Kirkland,  N.  Y. 
Bloomington,  111. 
Indian  Orchard,  Mass. 
Philadelphia,  Pa. 
Philadelphia,  Pa. 
Philadelphia,  Pa. 
Eaton,  N.  Y. 
Rome,  N.  Y. 
Torrington,  Conn. 
Denver,  Col, 
Westfield,  Mass. 
Lake  Linden,  Mich. 
South  Easton,  Pa. 
Wilmington,  Del. 
Philadelphia,  Pa. 
Cleveland,  O. 
Ashtabula,  O. 
Brooklyn,  N.  Y. 
Cleveland,  O. 
New  York  City. 


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Treatise  on  cranes 


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T7U 


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UNIVERSITY  OF   CALIFORNIA 
DAVIS 


